Seditio Source
Root |
./othercms/wordpress-6.0/wp-includes/wp-db.php
<?php
/**
 * WordPress database access abstraction class
 *
 * Original code from {@link http://php.justinvincent.com Justin Vincent (justin@visunet.ie)}
 *
 * @package WordPress
 * @subpackage Database
 * @since 0.71
 */

/**
 * @since 0.71
 */
define( 'EZSQL_VERSION', 'WP1.25' );

/**
 * @since 0.71
 */
define( 'OBJECT', 'OBJECT' );
// phpcs:ignore Generic.NamingConventions.UpperCaseConstantName.ConstantNotUpperCase
define( 'object', 'OBJECT' ); // Back compat.

/**
 * @since 2.5.0
 */
define( 'OBJECT_K', 'OBJECT_K' );

/**
 * @since 0.71
 */
define( 'ARRAY_A', 'ARRAY_A' );

/**
 * @since 0.71
 */
define( 'ARRAY_N', 'ARRAY_N' );

/**
 * WordPress database access abstraction class.
 *
 * This class is used to interact with a database without needing to use raw SQL statements.
 * By default, WordPress uses this class to instantiate the global $wpdb object, providing
 * access to the WordPress database.
 *
 * It is possible to replace this class with your own by setting the $wpdb global variable
 * in wp-content/db.php file to your class. The wpdb class will still be included, so you can
 * extend it or simply use your own.
 *
 * @link https://developer.wordpress.org/reference/classes/wpdb/
 *
 * @since 0.71
 */
class wpdb {

   
/**
     * Whether to show SQL/DB errors.
     *
     * Default is to show errors if both WP_DEBUG and WP_DEBUG_DISPLAY evaluate to true.
     *
     * @since 0.71
     *
     * @var bool
     */
   
public $show_errors = false;

   
/**
     * Whether to suppress errors during the DB bootstrapping. Default false.
     *
     * @since 2.5.0
     *
     * @var bool
     */
   
public $suppress_errors = false;

   
/**
     * The error encountered during the last query.
     *
     * @since 2.5.0
     *
     * @var string
     */
   
public $last_error = '';

   
/**
     * The number of queries made.
     *
     * @since 1.2.0
     *
     * @var int
     */
   
public $num_queries = 0;

   
/**
     * Count of rows returned by the last query.
     *
     * @since 0.71
     *
     * @var int
     */
   
public $num_rows = 0;

   
/**
     * Count of rows affected by the last query.
     *
     * @since 0.71
     *
     * @var int
     */
   
public $rows_affected = 0;

   
/**
     * The ID generated for an AUTO_INCREMENT column by the last query (usually INSERT).
     *
     * @since 0.71
     *
     * @var int
     */
   
public $insert_id = 0;

   
/**
     * The last query made.
     *
     * @since 0.71
     *
     * @var string
     */
   
public $last_query;

   
/**
     * Results of the last query.
     *
     * @since 0.71
     *
     * @var stdClass[]|null
     */
   
public $last_result;

   
/**
     * Database query result.
     *
     * Possible values:
     *
     * - For successful SELECT, SHOW, DESCRIBE, or EXPLAIN queries:
     *   - `mysqli_result` instance when the `mysqli` driver is in use
     *   - `resource` when the older `mysql` driver is in use
     * - `true` for other query types that were successful
     * - `null` if a query is yet to be made or if the result has since been flushed
     * - `false` if the query returned an error
     *
     * @since 0.71
     *
     * @var mysqli_result|resource|bool|null
     */
   
protected $result;

   
/**
     * Cached column info, for sanity checking data before inserting.
     *
     * @since 4.2.0
     *
     * @var array
     */
   
protected $col_meta = array();

   
/**
     * Calculated character sets keyed by table name.
     *
     * @since 4.2.0
     *
     * @var string[]
     */
   
protected $table_charset = array();

   
/**
     * Whether text fields in the current query need to be sanity checked.
     *
     * @since 4.2.0
     *
     * @var bool
     */
   
protected $check_current_query = true;

   
/**
     * Flag to ensure we don't run into recursion problems when checking the collation.
     *
     * @since 4.2.0
     *
     * @see wpdb::check_safe_collation()
     * @var bool
     */
   
private $checking_collation = false;

   
/**
     * Saved info on the table column.
     *
     * @since 0.71
     *
     * @var array
     */
   
protected $col_info;

   
/**
     * Log of queries that were executed, for debugging purposes.
     *
     * @since 1.5.0
     * @since 2.5.0 The third element in each query log was added to record the calling functions.
     * @since 5.1.0 The fourth element in each query log was added to record the start time.
     * @since 5.3.0 The fifth element in each query log was added to record custom data.
     *
     * @var array[] {
     *     Array of arrays containing information about queries that were executed.
     *
     *     @type array ...$0 {
     *         Data for each query.
     *
     *         @type string $0 The query's SQL.
     *         @type float  $1 Total time spent on the query, in seconds.
     *         @type string $2 Comma-separated list of the calling functions.
     *         @type float  $3 Unix timestamp of the time at the start of the query.
     *         @type array  $4 Custom query data.
     *     }
     * }
     */
   
public $queries;

   
/**
     * The number of times to retry reconnecting before dying. Default 5.
     *
     * @since 3.9.0
     *
     * @see wpdb::check_connection()
     * @var int
     */
   
protected $reconnect_retries = 5;

   
/**
     * WordPress table prefix.
     *
     * You can set this to have multiple WordPress installations in a single database.
     * The second reason is for possible security precautions.
     *
     * @since 2.5.0
     *
     * @var string
     */
   
public $prefix = '';

   
/**
     * WordPress base table prefix.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $base_prefix;

   
/**
     * Whether the database queries are ready to start executing.
     *
     * @since 2.3.2
     *
     * @var bool
     */
   
public $ready = false;

   
/**
     * Blog ID.
     *
     * @since 3.0.0
     *
     * @var int
     */
   
public $blogid = 0;

   
/**
     * Site ID.
     *
     * @since 3.0.0
     *
     * @var int
     */
   
public $siteid = 0;

   
/**
     * List of WordPress per-site tables.
     *
     * @since 2.5.0
     *
     * @see wpdb::tables()
     * @var string[]
     */
   
public $tables = array(
       
'posts',
       
'comments',
       
'links',
       
'options',
       
'postmeta',
       
'terms',
       
'term_taxonomy',
       
'term_relationships',
       
'termmeta',
       
'commentmeta',
    );

   
/**
     * List of deprecated WordPress tables.
     *
     * 'categories', 'post2cat', and 'link2cat' were deprecated in 2.3.0, db version 5539.
     *
     * @since 2.9.0
     *
     * @see wpdb::tables()
     * @var string[]
     */
   
public $old_tables = array( 'categories', 'post2cat', 'link2cat' );

   
/**
     * List of WordPress global tables.
     *
     * @since 3.0.0
     *
     * @see wpdb::tables()
     * @var string[]
     */
   
public $global_tables = array( 'users', 'usermeta' );

   
/**
     * List of Multisite global tables.
     *
     * @since 3.0.0
     *
     * @see wpdb::tables()
     * @var string[]
     */
   
public $ms_global_tables = array(
       
'blogs',
       
'blogmeta',
       
'signups',
       
'site',
       
'sitemeta',
       
'sitecategories',
       
'registration_log',
    );

   
/**
     * WordPress Comments table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $comments;

   
/**
     * WordPress Comment Metadata table.
     *
     * @since 2.9.0
     *
     * @var string
     */
   
public $commentmeta;

   
/**
     * WordPress Links table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $links;

   
/**
     * WordPress Options table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $options;

   
/**
     * WordPress Post Metadata table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $postmeta;

   
/**
     * WordPress Posts table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $posts;

   
/**
     * WordPress Terms table.
     *
     * @since 2.3.0
     *
     * @var string
     */
   
public $terms;

   
/**
     * WordPress Term Relationships table.
     *
     * @since 2.3.0
     *
     * @var string
     */
   
public $term_relationships;

   
/**
     * WordPress Term Taxonomy table.
     *
     * @since 2.3.0
     *
     * @var string
     */
   
public $term_taxonomy;

   
/**
     * WordPress Term Meta table.
     *
     * @since 4.4.0
     *
     * @var string
     */
   
public $termmeta;

   
//
    // Global and Multisite tables
    //

    /**
     * WordPress User Metadata table.
     *
     * @since 2.3.0
     *
     * @var string
     */
   
public $usermeta;

   
/**
     * WordPress Users table.
     *
     * @since 1.5.0
     *
     * @var string
     */
   
public $users;

   
/**
     * Multisite Blogs table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $blogs;

   
/**
     * Multisite Blog Metadata table.
     *
     * @since 5.1.0
     *
     * @var string
     */
   
public $blogmeta;

   
/**
     * Multisite Registration Log table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $registration_log;

   
/**
     * Multisite Signups table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $signups;

   
/**
     * Multisite Sites table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $site;

   
/**
     * Multisite Sitewide Terms table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $sitecategories;

   
/**
     * Multisite Site Metadata table.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $sitemeta;

   
/**
     * Format specifiers for DB columns.
     *
     * Columns not listed here default to %s. Initialized during WP load.
     * Keys are column names, values are format types: 'ID' => '%d'.
     *
     * @since 2.8.0
     *
     * @see wpdb::prepare()
     * @see wpdb::insert()
     * @see wpdb::update()
     * @see wpdb::delete()
     * @see wp_set_wpdb_vars()
     * @var array
     */
   
public $field_types = array();

   
/**
     * Database table columns charset.
     *
     * @since 2.2.0
     *
     * @var string
     */
   
public $charset;

   
/**
     * Database table columns collate.
     *
     * @since 2.2.0
     *
     * @var string
     */
   
public $collate;

   
/**
     * Database Username.
     *
     * @since 2.9.0
     *
     * @var string
     */
   
protected $dbuser;

   
/**
     * Database Password.
     *
     * @since 3.1.0
     *
     * @var string
     */
   
protected $dbpassword;

   
/**
     * Database Name.
     *
     * @since 3.1.0
     *
     * @var string
     */
   
protected $dbname;

   
/**
     * Database Host.
     *
     * @since 3.1.0
     *
     * @var string
     */
   
protected $dbhost;

   
/**
     * Database handle.
     *
     * Possible values:
     *
     * - `mysqli` instance when the `mysqli` driver is in use
     * - `resource` when the older `mysql` driver is in use
     * - `null` if the connection is yet to be made or has been closed
     * - `false` if the connection has failed
     *
     * @since 0.71
     *
     * @var mysqli|resource|false|null
     */
   
protected $dbh;

   
/**
     * A textual description of the last query/get_row/get_var call.
     *
     * @since 3.0.0
     *
     * @var string
     */
   
public $func_call;

   
/**
     * Whether MySQL is used as the database engine.
     *
     * Set in wpdb::db_connect() to true, by default. This is used when checking
     * against the required MySQL version for WordPress. Normally, a replacement
     * database drop-in (db.php) will skip these checks, but setting this to true
     * will force the checks to occur.
     *
     * @since 3.3.0
     *
     * @var bool
     */
   
public $is_mysql = null;

   
/**
     * A list of incompatible SQL modes.
     *
     * @since 3.9.0
     *
     * @var string[]
     */
   
protected $incompatible_modes = array(
       
'NO_ZERO_DATE',
       
'ONLY_FULL_GROUP_BY',
       
'STRICT_TRANS_TABLES',
       
'STRICT_ALL_TABLES',
       
'TRADITIONAL',
       
'ANSI',
    );

   
/**
     * Whether to use mysqli over mysql. Default false.
     *
     * @since 3.9.0
     *
     * @var bool
     */
   
private $use_mysqli = false;

   
/**
     * Whether we've managed to successfully connect at some point.
     *
     * @since 3.9.0
     *
     * @var bool
     */
   
private $has_connected = false;

   
/**
     * Time when the last query was performed.
     *
     * Only set when `SAVEQUERIES` is defined and truthy.
     *
     * @since 1.5.0
     *
     * @var float
     */
   
public $time_start = null;

   
/**
     * The last SQL error that was encountered.
     *
     * @since 2.5.0
     *
     * @var WP_Error|string
     */
   
public $error = null;

   
/**
     * Connects to the database server and selects a database.
     *
     * Does the actual setting up
     * of the class properties and connection to the database.
     *
     * @since 2.0.8
     *
     * @link https://core.trac.wordpress.org/ticket/3354
     *
     * @param string $dbuser     Database user.
     * @param string $dbpassword Database password.
     * @param string $dbname     Database name.
     * @param string $dbhost     Database host.
     */
   
public function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {
        if (
WP_DEBUG && WP_DEBUG_DISPLAY ) {
           
$this->show_errors();
        }

       
// Use the `mysqli` extension if it exists unless `WP_USE_EXT_MYSQL` is defined as true.
       
if ( function_exists( 'mysqli_connect' ) ) {
           
$this->use_mysqli = true;

            if (
defined( 'WP_USE_EXT_MYSQL' ) ) {
               
$this->use_mysqli = ! WP_USE_EXT_MYSQL;
            }
        }

       
$this->dbuser     = $dbuser;
       
$this->dbpassword = $dbpassword;
       
$this->dbname     = $dbname;
       
$this->dbhost     = $dbhost;

       
// wp-config.php creation will manually connect when ready.
       
if ( defined( 'WP_SETUP_CONFIG' ) ) {
            return;
        }

       
$this->db_connect();
    }

   
/**
     * Makes private properties readable for backward compatibility.
     *
     * @since 3.5.0
     *
     * @param string $name The private member to get, and optionally process.
     * @return mixed The private member.
     */
   
public function __get( $name ) {
        if (
'col_info' === $name ) {
           
$this->load_col_info();
        }

        return
$this->$name;
    }

   
/**
     * Makes private properties settable for backward compatibility.
     *
     * @since 3.5.0
     *
     * @param string $name  The private member to set.
     * @param mixed  $value The value to set.
     */
   
public function __set( $name, $value ) {
       
$protected_members = array(
           
'col_meta',
           
'table_charset',
           
'check_current_query',
        );
        if (
in_array( $name, $protected_members, true ) ) {
            return;
        }
       
$this->$name = $value;
    }

   
/**
     * Makes private properties check-able for backward compatibility.
     *
     * @since 3.5.0
     *
     * @param string $name The private member to check.
     * @return bool If the member is set or not.
     */
   
public function __isset( $name ) {
        return isset(
$this->$name );
    }

   
/**
     * Makes private properties un-settable for backward compatibility.
     *
     * @since 3.5.0
     *
     * @param string $name  The private member to unset
     */
   
public function __unset( $name ) {
        unset(
$this->$name );
    }

   
/**
     * Sets $this->charset and $this->collate.
     *
     * @since 3.1.0
     */
   
public function init_charset() {
       
$charset = '';
       
$collate = '';

        if (
function_exists( 'is_multisite' ) && is_multisite() ) {
           
$charset = 'utf8';
            if (
defined( 'DB_COLLATE' ) && DB_COLLATE ) {
               
$collate = DB_COLLATE;
            } else {
               
$collate = 'utf8_general_ci';
            }
        } elseif (
defined( 'DB_COLLATE' ) ) {
           
$collate = DB_COLLATE;
        }

        if (
defined( 'DB_CHARSET' ) ) {
           
$charset = DB_CHARSET;
        }

       
$charset_collate = $this->determine_charset( $charset, $collate );

       
$this->charset = $charset_collate['charset'];
       
$this->collate = $charset_collate['collate'];
    }

   
/**
     * Determines the best charset and collation to use given a charset and collation.
     *
     * For example, when able, utf8mb4 should be used instead of utf8.
     *
     * @since 4.6.0
     *
     * @param string $charset The character set to check.
     * @param string $collate The collation to check.
     * @return array {
     *     The most appropriate character set and collation to use.
     *
     *     @type string $charset Character set.
     *     @type string $collate Collation.
     * }
     */
   
public function determine_charset( $charset, $collate ) {
        if ( (
$this->use_mysqli && ! ( $this->dbh instanceof mysqli ) ) || empty( $this->dbh ) ) {
            return
compact( 'charset', 'collate' );
        }

        if (
'utf8' === $charset && $this->has_cap( 'utf8mb4' ) ) {
           
$charset = 'utf8mb4';
        }

        if (
'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
           
$charset = 'utf8';
           
$collate = str_replace( 'utf8mb4_', 'utf8_', $collate );
        }

        if (
'utf8mb4' === $charset ) {
           
// _general_ is outdated, so we can upgrade it to _unicode_, instead.
           
if ( ! $collate || 'utf8_general_ci' === $collate ) {
               
$collate = 'utf8mb4_unicode_ci';
            } else {
               
$collate = str_replace( 'utf8_', 'utf8mb4_', $collate );
            }
        }

       
// _unicode_520_ is a better collation, we should use that when it's available.
       
if ( $this->has_cap( 'utf8mb4_520' ) && 'utf8mb4_unicode_ci' === $collate ) {
           
$collate = 'utf8mb4_unicode_520_ci';
        }

        return
compact( 'charset', 'collate' );
    }

   
/**
     * Sets the connection's character set.
     *
     * @since 3.1.0
     *
     * @param mysqli|resource $dbh     The connection returned by `mysqli_connect()` or `mysql_connect()`.
     * @param string          $charset Optional. The character set. Default null.
     * @param string          $collate Optional. The collation. Default null.
     */
   
public function set_charset( $dbh, $charset = null, $collate = null ) {
        if ( ! isset(
$charset ) ) {
           
$charset = $this->charset;
        }
        if ( ! isset(
$collate ) ) {
           
$collate = $this->collate;
        }
        if (
$this->has_cap( 'collation' ) && ! empty( $charset ) ) {
           
$set_charset_succeeded = true;

            if (
$this->use_mysqli ) {
                if (
function_exists( 'mysqli_set_charset' ) && $this->has_cap( 'set_charset' ) ) {
                   
$set_charset_succeeded = mysqli_set_charset( $dbh, $charset );
                }

                if (
$set_charset_succeeded ) {
                   
$query = $this->prepare( 'SET NAMES %s', $charset );
                    if ( ! empty(
$collate ) ) {
                       
$query .= $this->prepare( ' COLLATE %s', $collate );
                    }
                   
mysqli_query( $dbh, $query );
                }
            } else {
                if (
function_exists( 'mysql_set_charset' ) && $this->has_cap( 'set_charset' ) ) {
                   
$set_charset_succeeded = mysql_set_charset( $charset, $dbh );
                }
                if (
$set_charset_succeeded ) {
                   
$query = $this->prepare( 'SET NAMES %s', $charset );
                    if ( ! empty(
$collate ) ) {
                       
$query .= $this->prepare( ' COLLATE %s', $collate );
                    }
                   
mysql_query( $query, $dbh );
                }
            }
        }
    }

   
/**
     * Changes the current SQL mode, and ensures its WordPress compatibility.
     *
     * If no modes are passed, it will ensure the current MySQL server modes are compatible.
     *
     * @since 3.9.0
     *
     * @param array $modes Optional. A list of SQL modes to set. Default empty array.
     */
   
public function set_sql_mode( $modes = array() ) {
        if ( empty(
$modes ) ) {
            if (
$this->use_mysqli ) {
               
$res = mysqli_query( $this->dbh, 'SELECT @@SESSION.sql_mode' );
            } else {
               
$res = mysql_query( 'SELECT @@SESSION.sql_mode', $this->dbh );
            }

            if ( empty(
$res ) ) {
                return;
            }

            if (
$this->use_mysqli ) {
               
$modes_array = mysqli_fetch_array( $res );
                if ( empty(
$modes_array[0] ) ) {
                    return;
                }
               
$modes_str = $modes_array[0];
            } else {
               
$modes_str = mysql_result( $res, 0 );
            }

            if ( empty(
$modes_str ) ) {
                return;
            }

           
$modes = explode( ',', $modes_str );
        }

       
$modes = array_change_key_case( $modes, CASE_UPPER );

       
/**
         * Filters the list of incompatible SQL modes to exclude.
         *
         * @since 3.9.0
         *
         * @param array $incompatible_modes An array of incompatible modes.
         */
       
$incompatible_modes = (array) apply_filters( 'incompatible_sql_modes', $this->incompatible_modes );

        foreach (
$modes as $i => $mode ) {
            if (
in_array( $mode, $incompatible_modes, true ) ) {
                unset(
$modes[ $i ] );
            }
        }

       
$modes_str = implode( ',', $modes );

        if (
$this->use_mysqli ) {
           
mysqli_query( $this->dbh, "SET SESSION sql_mode='$modes_str'" );
        } else {
           
mysql_query( "SET SESSION sql_mode='$modes_str'", $this->dbh );
        }
    }

   
/**
     * Sets the table prefix for the WordPress tables.
     *
     * @since 2.5.0
     *
     * @param string $prefix          Alphanumeric name for the new prefix.
     * @param bool   $set_table_names Optional. Whether the table names, e.g. wpdb::$posts,
     *                                should be updated or not. Default true.
     * @return string|WP_Error Old prefix or WP_Error on error.
     */
   
public function set_prefix( $prefix, $set_table_names = true ) {

        if (
preg_match( '|[^a-z0-9_]|i', $prefix ) ) {
            return new
WP_Error( 'invalid_db_prefix', 'Invalid database prefix' );
        }

       
$old_prefix = is_multisite() ? '' : $prefix;

        if ( isset(
$this->base_prefix ) ) {
           
$old_prefix = $this->base_prefix;
        }

       
$this->base_prefix = $prefix;

        if (
$set_table_names ) {
            foreach (
$this->tables( 'global' ) as $table => $prefixed_table ) {
               
$this->$table = $prefixed_table;
            }

            if (
is_multisite() && empty( $this->blogid ) ) {
                return
$old_prefix;
            }

           
$this->prefix = $this->get_blog_prefix();

            foreach (
$this->tables( 'blog' ) as $table => $prefixed_table ) {
               
$this->$table = $prefixed_table;
            }

            foreach (
$this->tables( 'old' ) as $table => $prefixed_table ) {
               
$this->$table = $prefixed_table;
            }
        }
        return
$old_prefix;
    }

   
/**
     * Sets blog ID.
     *
     * @since 3.0.0
     *
     * @param int $blog_id
     * @param int $network_id Optional.
     * @return int Previous blog ID.
     */
   
public function set_blog_id( $blog_id, $network_id = 0 ) {
        if ( ! empty(
$network_id ) ) {
           
$this->siteid = $network_id;
        }

       
$old_blog_id  = $this->blogid;
       
$this->blogid = $blog_id;

       
$this->prefix = $this->get_blog_prefix();

        foreach (
$this->tables( 'blog' ) as $table => $prefixed_table ) {
           
$this->$table = $prefixed_table;
        }

        foreach (
$this->tables( 'old' ) as $table => $prefixed_table ) {
           
$this->$table = $prefixed_table;
        }

        return
$old_blog_id;
    }

   
/**
     * Gets blog prefix.
     *
     * @since 3.0.0
     *
     * @param int $blog_id Optional.
     * @return string Blog prefix.
     */
   
public function get_blog_prefix( $blog_id = null ) {
        if (
is_multisite() ) {
            if (
null === $blog_id ) {
               
$blog_id = $this->blogid;
            }

           
$blog_id = (int) $blog_id;

            if (
defined( 'MULTISITE' ) && ( 0 === $blog_id || 1 === $blog_id ) ) {
                return
$this->base_prefix;
            } else {
                return
$this->base_prefix . $blog_id . '_';
            }
        } else {
            return
$this->base_prefix;
        }
    }

   
/**
     * Returns an array of WordPress tables.
     *
     * Also allows for the `CUSTOM_USER_TABLE` and `CUSTOM_USER_META_TABLE` to override the WordPress users
     * and usermeta tables that would otherwise be determined by the prefix.
     *
     * The `$scope` argument can take one of the following:
     *
     * - 'all' - returns 'all' and 'global' tables. No old tables are returned.
     * - 'blog' - returns the blog-level tables for the queried blog.
     * - 'global' - returns the global tables for the installation, returning multisite tables only on multisite.
     * - 'ms_global' - returns the multisite global tables, regardless if current installation is multisite.
     * - 'old' - returns tables which are deprecated.
     *
     * @since 3.0.0
     *
     * @uses wpdb::$tables
     * @uses wpdb::$old_tables
     * @uses wpdb::$global_tables
     * @uses wpdb::$ms_global_tables
     *
     * @param string $scope   Optional. Possible values include 'all', 'global', 'ms_global', 'blog',
     *                        or 'old' tables. Default 'all'.
     * @param bool   $prefix  Optional. Whether to include table prefixes. If blog prefix is requested,
     *                        then the custom users and usermeta tables will be mapped. Default true.
     * @param int    $blog_id Optional. The blog_id to prefix. Used only when prefix is requested.
     *                        Defaults to `wpdb::$blogid`.
     * @return string[] Table names. When a prefix is requested, the key is the unprefixed table name.
     */
   
public function tables( $scope = 'all', $prefix = true, $blog_id = 0 ) {
        switch (
$scope ) {
            case
'all':
               
$tables = array_merge( $this->global_tables, $this->tables );
                if (
is_multisite() ) {
                   
$tables = array_merge( $tables, $this->ms_global_tables );
                }
                break;
            case
'blog':
               
$tables = $this->tables;
                break;
            case
'global':
               
$tables = $this->global_tables;
                if (
is_multisite() ) {
                   
$tables = array_merge( $tables, $this->ms_global_tables );
                }
                break;
            case
'ms_global':
               
$tables = $this->ms_global_tables;
                break;
            case
'old':
               
$tables = $this->old_tables;
                break;
            default:
                return array();
        }

        if (
$prefix ) {
            if ( !
$blog_id ) {
               
$blog_id = $this->blogid;
            }
           
$blog_prefix   = $this->get_blog_prefix( $blog_id );
           
$base_prefix   = $this->base_prefix;
           
$global_tables = array_merge( $this->global_tables, $this->ms_global_tables );
            foreach (
$tables as $k => $table ) {
                if (
in_array( $table, $global_tables, true ) ) {
                   
$tables[ $table ] = $base_prefix . $table;
                } else {
                   
$tables[ $table ] = $blog_prefix . $table;
                }
                unset(
$tables[ $k ] );
            }

            if ( isset(
$tables['users'] ) && defined( 'CUSTOM_USER_TABLE' ) ) {
               
$tables['users'] = CUSTOM_USER_TABLE;
            }

            if ( isset(
$tables['usermeta'] ) && defined( 'CUSTOM_USER_META_TABLE' ) ) {
               
$tables['usermeta'] = CUSTOM_USER_META_TABLE;
            }
        }

        return
$tables;
    }

   
/**
     * Selects a database using the current or provided database connection.
     *
     * The database name will be changed based on the current database connection.
     * On failure, the execution will bail and display a DB error.
     *
     * @since 0.71
     *
     * @param string          $db  Database name.
     * @param mysqli|resource $dbh Optional database connection.
     */
   
public function select( $db, $dbh = null ) {
        if (
is_null( $dbh ) ) {
           
$dbh = $this->dbh;
        }

        if (
$this->use_mysqli ) {
           
$success = mysqli_select_db( $dbh, $db );
        } else {
           
$success = mysql_select_db( $db, $dbh );
        }
        if ( !
$success ) {
           
$this->ready = false;
            if ( !
did_action( 'template_redirect' ) ) {
               
wp_load_translations_early();

               
$message = '<h1>' . __( 'Cannot select database' ) . "</h1>\n";

               
$message .= '<p>' . sprintf(
                   
/* translators: %s: Database name. */
                   
__( 'The database server could be connected to (which means your username and password is okay) but the %s database could not be selected.' ),
                   
'<code>' . htmlspecialchars( $db, ENT_QUOTES ) . '</code>'
               
) . "</p>\n";

               
$message .= "<ul>\n";
               
$message .= '<li>' . __( 'Are you sure it exists?' ) . "</li>\n";

               
$message .= '<li>' . sprintf(
                   
/* translators: 1: Database user, 2: Database name. */
                   
__( 'Does the user %1$s have permission to use the %2$s database?' ),
                   
'<code>' . htmlspecialchars( $this->dbuser, ENT_QUOTES ) . '</code>',
                   
'<code>' . htmlspecialchars( $db, ENT_QUOTES ) . '</code>'
               
) . "</li>\n";

               
$message .= '<li>' . sprintf(
                   
/* translators: %s: Database name. */
                   
__( 'On some systems the name of your database is prefixed with your username, so it would be like <code>username_%1$s</code>. Could that be the problem?' ),
                   
htmlspecialchars( $db, ENT_QUOTES )
                ) .
"</li>\n";

               
$message .= "</ul>\n";

               
$message .= '<p>' . sprintf(
                   
/* translators: %s: Support forums URL. */
                   
__( 'If you do not know how to set up a database you should <strong>contact your host</strong>. If all else fails you may find help at the <a href="%s">WordPress Support Forums</a>.' ),
                   
__( 'https://wordpress.org/support/forums/' )
                ) .
"</p>\n";

               
$this->bail( $message, 'db_select_fail' );
            }
        }
    }

   
/**
     * Do not use, deprecated.
     *
     * Use esc_sql() or wpdb::prepare() instead.
     *
     * @since 2.8.0
     * @deprecated 3.6.0 Use wpdb::prepare()
     * @see wpdb::prepare()
     * @see esc_sql()
     *
     * @param string $string
     * @return string
     */
   
public function _weak_escape( $string ) {
        if (
func_num_args() === 1 && function_exists( '_deprecated_function' ) ) {
           
_deprecated_function( __METHOD__, '3.6.0', 'wpdb::prepare() or esc_sql()' );
        }
        return
addslashes( $string );
    }

   
/**
     * Real escape, using mysqli_real_escape_string() or mysql_real_escape_string().
     *
     * @since 2.8.0
     *
     * @see mysqli_real_escape_string()
     * @see mysql_real_escape_string()
     *
     * @param string $string String to escape.
     * @return string Escaped string.
     */
   
public function _real_escape( $string ) {
        if ( !
is_scalar( $string ) ) {
            return
'';
        }

        if (
$this->dbh ) {
            if (
$this->use_mysqli ) {
               
$escaped = mysqli_real_escape_string( $this->dbh, $string );
            } else {
               
$escaped = mysql_real_escape_string( $string, $this->dbh );
            }
        } else {
           
$class = get_class( $this );

           
wp_load_translations_early();
           
/* translators: %s: Database access abstraction class, usually wpdb or a class extending wpdb. */
           
_doing_it_wrong( $class, sprintf( __( '%s must set a database connection for use with escaping.' ), $class ), '3.6.0' );

           
$escaped = addslashes( $string );
        }

        return
$this->add_placeholder_escape( $escaped );
    }

   
/**
     * Escapes data. Works on arrays.
     *
     * @since 2.8.0
     *
     * @uses wpdb::_real_escape()
     *
     * @param string|array $data Data to escape.
     * @return string|array Escaped data, in the same type as supplied.
     */
   
public function _escape( $data ) {
        if (
is_array( $data ) ) {
            foreach (
$data as $k => $v ) {
                if (
is_array( $v ) ) {
                   
$data[ $k ] = $this->_escape( $v );
                } else {
                   
$data[ $k ] = $this->_real_escape( $v );
                }
            }
        } else {
           
$data = $this->_real_escape( $data );
        }

        return
$data;
    }

   
/**
     * Do not use, deprecated.
     *
     * Use esc_sql() or wpdb::prepare() instead.
     *
     * @since 0.71
     * @deprecated 3.6.0 Use wpdb::prepare()
     * @see wpdb::prepare()
     * @see esc_sql()
     *
     * @param string|array $data Data to escape.
     * @return string|array Escaped data, in the same type as supplied.
     */
   
public function escape( $data ) {
        if (
func_num_args() === 1 && function_exists( '_deprecated_function' ) ) {
           
_deprecated_function( __METHOD__, '3.6.0', 'wpdb::prepare() or esc_sql()' );
        }
        if (
is_array( $data ) ) {
            foreach (
$data as $k => $v ) {
                if (
is_array( $v ) ) {
                   
$data[ $k ] = $this->escape( $v, 'recursive' );
                } else {
                   
$data[ $k ] = $this->_weak_escape( $v, 'internal' );
                }
            }
        } else {
           
$data = $this->_weak_escape( $data, 'internal' );
        }

        return
$data;
    }

   
/**
     * Escapes content by reference for insertion into the database, for security.
     *
     * @uses wpdb::_real_escape()
     *
     * @since 2.3.0
     *
     * @param string $string String to escape.
     */
   
public function escape_by_ref( &$string ) {
        if ( !
is_float( $string ) ) {
           
$string = $this->_real_escape( $string );
        }
    }

   
/**
     * Prepares a SQL query for safe execution.
     *
     * Uses sprintf()-like syntax. The following placeholders can be used in the query string:
     *
     * - %d (integer)
     * - %f (float)
     * - %s (string)
     *
     * All placeholders MUST be left unquoted in the query string. A corresponding argument
     * MUST be passed for each placeholder.
     *
     * Note: There is one exception to the above: for compatibility with old behavior,
     * numbered or formatted string placeholders (eg, `%1$s`, `%5s`) will not have quotes
     * added by this function, so should be passed with appropriate quotes around them.
     *
     * Literal percentage signs (`%`) in the query string must be written as `%%`. Percentage wildcards
     * (for example, to use in LIKE syntax) must be passed via a substitution argument containing
     * the complete LIKE string, these cannot be inserted directly in the query string.
     * Also see wpdb::esc_like().
     *
     * Arguments may be passed as individual arguments to the method, or as a single array
     * containing all arguments. A combination of the two is not supported.
     *
     * Examples:
     *
     *     $wpdb->prepare( "SELECT * FROM `table` WHERE `column` = %s AND `field` = %d OR `other_field` LIKE %s", array( 'foo', 1337, '%bar' ) );
     *     $wpdb->prepare( "SELECT DATE_FORMAT(`field`, '%%c') FROM `table` WHERE `column` = %s", 'foo' );
     *
     * @since 2.3.0
     * @since 5.3.0 Formalized the existing and already documented `...$args` parameter
     *              by updating the function signature. The second parameter was changed
     *              from `$args` to `...$args`.
     *
     * @link https://www.php.net/sprintf Description of syntax.
     *
     * @param string      $query   Query statement with sprintf()-like placeholders.
     * @param array|mixed $args    The array of variables to substitute into the query's placeholders
     *                             if being called with an array of arguments, or the first variable
     *                             to substitute into the query's placeholders if being called with
     *                             individual arguments.
     * @param mixed       ...$args Further variables to substitute into the query's placeholders
     *                             if being called with individual arguments.
     * @return string|void Sanitized query string, if there is a query to prepare.
     */
   
public function prepare( $query, ...$args ) {
        if (
is_null( $query ) ) {
            return;
        }

       
// This is not meant to be foolproof -- but it will catch obviously incorrect usage.
       
if ( strpos( $query, '%' ) === false ) {
           
wp_load_translations_early();
           
_doing_it_wrong(
               
'wpdb::prepare',
               
sprintf(
                   
/* translators: %s: wpdb::prepare() */
                   
__( 'The query argument of %s must have a placeholder.' ),
                   
'wpdb::prepare()'
               
),
               
'3.9.0'
           
);
        }

       
// If args were passed as an array (as in vsprintf), move them up.
       
$passed_as_array = false;
        if ( isset(
$args[0] ) && is_array( $args[0] ) && 1 === count( $args ) ) {
           
$passed_as_array = true;
           
$args            = $args[0];
        }

        foreach (
$args as $arg ) {
            if ( !
is_scalar( $arg ) && ! is_null( $arg ) ) {
               
wp_load_translations_early();
               
_doing_it_wrong(
                   
'wpdb::prepare',
                   
sprintf(
                       
/* translators: %s: Value type. */
                       
__( 'Unsupported value type (%s).' ),
                       
gettype( $arg )
                    ),
                   
'4.8.2'
               
);
            }
        }

       
/*
         * Specify the formatting allowed in a placeholder. The following are allowed:
         *
         * - Sign specifier. eg, $+d
         * - Numbered placeholders. eg, %1$s
         * - Padding specifier, including custom padding characters. eg, %05s, %'#5s
         * - Alignment specifier. eg, %05-s
         * - Precision specifier. eg, %.2f
         */
       
$allowed_format = '(?:[1-9][0-9]*[$])?[-+0-9]*(?: |0|\'.)?[-+0-9]*(?:\.[0-9]+)?';

       
/*
         * If a %s placeholder already has quotes around it, removing the existing quotes and re-inserting them
         * ensures the quotes are consistent.
         *
         * For backward compatibility, this is only applied to %s, and not to placeholders like %1$s, which are frequently
         * used in the middle of longer strings, or as table name placeholders.
         */
       
$query = str_replace( "'%s'", '%s', $query ); // Strip any existing single quotes.
       
$query = str_replace( '"%s"', '%s', $query ); // Strip any existing double quotes.
       
$query = preg_replace( '/(?<!%)%s/', "'%s'", $query ); // Quote the strings, avoiding escaped strings like %%s.

       
$query = preg_replace( "/(?<!%)(%($allowed_format)?f)/", '%\\2F', $query ); // Force floats to be locale-unaware.

       
$query = preg_replace( "/%(?:%|$|(?!($allowed_format)?[sdF]))/", '%%\\1', $query ); // Escape any unescaped percents.

        // Count the number of valid placeholders in the query.
       
$placeholders = preg_match_all( "/(^|[^%]|(%%)+)%($allowed_format)?[sdF]/", $query, $matches );

       
$args_count = count( $args );

        if (
$args_count !== $placeholders ) {
            if (
1 === $placeholders && $passed_as_array ) {
               
// If the passed query only expected one argument, but the wrong number of arguments were sent as an array, bail.
               
wp_load_translations_early();
               
_doing_it_wrong(
                   
'wpdb::prepare',
                   
__( 'The query only expected one placeholder, but an array of multiple placeholders was sent.' ),
                   
'4.9.0'
               
);

                return;
            } else {
               
/*
                 * If we don't have the right number of placeholders, but they were passed as individual arguments,
                 * or we were expecting multiple arguments in an array, throw a warning.
                 */
               
wp_load_translations_early();
               
_doing_it_wrong(
                   
'wpdb::prepare',
                   
sprintf(
                       
/* translators: 1: Number of placeholders, 2: Number of arguments passed. */
                       
__( 'The query does not contain the correct number of placeholders (%1$d) for the number of arguments passed (%2$d).' ),
                       
$placeholders,
                       
$args_count
                   
),
                   
'4.8.3'
               
);

               
/*
                 * If we don't have enough arguments to match the placeholders,
                 * return an empty string to avoid a fatal error on PHP 8.
                 */
               
if ( $args_count < $placeholders ) {
                   
$max_numbered_placeholder = ! empty( $matches[3] ) ? max( array_map( 'intval', $matches[3] ) ) : 0;

                    if ( !
$max_numbered_placeholder || $args_count < $max_numbered_placeholder ) {
                        return
'';
                    }
                }
            }
        }

       
array_walk( $args, array( $this, 'escape_by_ref' ) );
       
$query = vsprintf( $query, $args );

        return
$this->add_placeholder_escape( $query );
    }

   
/**
     * First half of escaping for `LIKE` special characters `%` and `_` before preparing for SQL.
     *
     * Use this only before wpdb::prepare() or esc_sql(). Reversing the order is very bad for security.
     *
     * Example Prepared Statement:
     *
     *     $wild = '%';
     *     $find = 'only 43% of planets';
     *     $like = $wild . $wpdb->esc_like( $find ) . $wild;
     *     $sql  = $wpdb->prepare( "SELECT * FROM $wpdb->posts WHERE post_content LIKE %s", $like );
     *
     * Example Escape Chain:
     *
     *     $sql  = esc_sql( $wpdb->esc_like( $input ) );
     *
     * @since 4.0.0
     *
     * @param string $text The raw text to be escaped. The input typed by the user
     *                     should have no extra or deleted slashes.
     * @return string Text in the form of a LIKE phrase. The output is not SQL safe.
     *                Call wpdb::prepare() or wpdb::_real_escape() next.
     */
   
public function esc_like( $text ) {
        return
addcslashes( $text, '_%\\' );
    }

   
/**
     * Prints SQL/DB error.
     *
     * @since 0.71
     *
     * @global array $EZSQL_ERROR Stores error information of query and error string.
     *
     * @param string $str The error to display.
     * @return void|false Void if the showing of errors is enabled, false if disabled.
     */
   
public function print_error( $str = '' ) {
        global
$EZSQL_ERROR;

        if ( !
$str ) {
            if (
$this->use_mysqli ) {
               
$str = mysqli_error( $this->dbh );
            } else {
               
$str = mysql_error( $this->dbh );
            }
        }
       
$EZSQL_ERROR[] = array(
           
'query'     => $this->last_query,
           
'error_str' => $str,
        );

        if (
$this->suppress_errors ) {
            return
false;
        }

       
wp_load_translations_early();

       
$caller = $this->get_caller();
        if (
$caller ) {
           
/* translators: 1: Database error message, 2: SQL query, 3: Name of the calling function. */
           
$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s made by %3$s' ), $str, $this->last_query, $caller );
        } else {
           
/* translators: 1: Database error message, 2: SQL query. */
           
$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s' ), $str, $this->last_query );
        }

       
error_log( $error_str );

       
// Are we showing errors?
       
if ( ! $this->show_errors ) {
            return
false;
        }

       
// If there is an error then take note of it.
       
if ( is_multisite() ) {
           
$msg = sprintf(
               
"%s [%s]\n%s\n",
               
__( 'WordPress database error:' ),
               
$str,
               
$this->last_query
           
);

            if (
defined( 'ERRORLOGFILE' ) ) {
               
error_log( $msg, 3, ERRORLOGFILE );
            }
            if (
defined( 'DIEONDBERROR' ) ) {
               
wp_die( $msg );
            }
        } else {
           
$str   = htmlspecialchars( $str, ENT_QUOTES );
           
$query = htmlspecialchars( $this->last_query, ENT_QUOTES );

           
printf(
               
'<div id="error"><p class="wpdberror"><strong>%s</strong> [%s]<br /><code>%s</code></p></div>',
               
__( 'WordPress database error:' ),
               
$str,
               
$query
           
);
        }
    }

   
/**
     * Enables showing of database errors.
     *
     * This function should be used only to enable showing of errors.
     * wpdb::hide_errors() should be used instead for hiding errors.
     *
     * @since 0.71
     *
     * @see wpdb::hide_errors()
     *
     * @param bool $show Optional. Whether to show errors. Default true.
     * @return bool Whether showing of errors was previously active.
     */
   
public function show_errors( $show = true ) {
       
$errors            = $this->show_errors;
       
$this->show_errors = $show;
        return
$errors;
    }

   
/**
     * Disables showing of database errors.
     *
     * By default database errors are not shown.
     *
     * @since 0.71
     *
     * @see wpdb::show_errors()
     *
     * @return bool Whether showing of errors was previously active.
     */
   
public function hide_errors() {
       
$show              = $this->show_errors;
       
$this->show_errors = false;
        return
$show;
    }

   
/**
     * Enables or disables suppressing of database errors.
     *
     * By default database errors are suppressed.
     *
     * @since 2.5.0
     *
     * @see wpdb::hide_errors()
     *
     * @param bool $suppress Optional. Whether to suppress errors. Default true.
     * @return bool Whether suppressing of errors was previously active.
     */
   
public function suppress_errors( $suppress = true ) {
       
$errors                = $this->suppress_errors;
       
$this->suppress_errors = (bool) $suppress;
        return
$errors;
    }

   
/**
     * Kills cached query results.
     *
     * @since 0.71
     */
   
public function flush() {
       
$this->last_result   = array();
       
$this->col_info      = null;
       
$this->last_query    = null;
       
$this->rows_affected = 0;
       
$this->num_rows      = 0;
       
$this->last_error    = '';

        if (
$this->use_mysqli && $this->result instanceof mysqli_result ) {
           
mysqli_free_result( $this->result );
           
$this->result = null;

           
// Sanity check before using the handle.
           
if ( empty( $this->dbh ) || ! ( $this->dbh instanceof mysqli ) ) {
                return;
            }

           
// Clear out any results from a multi-query.
           
while ( mysqli_more_results( $this->dbh ) ) {
               
mysqli_next_result( $this->dbh );
            }
        } elseif (
is_resource( $this->result ) ) {
           
mysql_free_result( $this->result );
        }
    }

   
/**
     * Connects to and selects database.
     *
     * If `$allow_bail` is false, the lack of database connection will need to be handled manually.
     *
     * @since 3.0.0
     * @since 3.9.0 $allow_bail parameter added.
     *
     * @param bool $allow_bail Optional. Allows the function to bail. Default true.
     * @return bool True with a successful connection, false on failure.
     */
   
public function db_connect( $allow_bail = true ) {
       
$this->is_mysql = true;

       
/*
         * Deprecated in 3.9+ when using MySQLi. No equivalent
         * $new_link parameter exists for mysqli_* functions.
         */
       
$new_link     = defined( 'MYSQL_NEW_LINK' ) ? MYSQL_NEW_LINK : true;
       
$client_flags = defined( 'MYSQL_CLIENT_FLAGS' ) ? MYSQL_CLIENT_FLAGS : 0;

        if (
$this->use_mysqli ) {
           
/*
             * Set the MySQLi error reporting off because WordPress handles its own.
             * This is due to the default value change from `MYSQLI_REPORT_OFF`
             * to `MYSQLI_REPORT_ERROR|MYSQLI_REPORT_STRICT` in PHP 8.1.
             */
           
mysqli_report( MYSQLI_REPORT_OFF );

           
$this->dbh = mysqli_init();

           
$host    = $this->dbhost;
           
$port    = null;
           
$socket  = null;
           
$is_ipv6 = false;

           
$host_data = $this->parse_db_host( $this->dbhost );
            if (
$host_data ) {
                list(
$host, $port, $socket, $is_ipv6 ) = $host_data;
            }

           
/*
             * If using the `mysqlnd` library, the IPv6 address needs to be enclosed
             * in square brackets, whereas it doesn't while using the `libmysqlclient` library.
             * @see https://bugs.php.net/bug.php?id=67563
             */
           
if ( $is_ipv6 && extension_loaded( 'mysqlnd' ) ) {
               
$host = "[$host]";
            }

            if (
WP_DEBUG ) {
               
mysqli_real_connect( $this->dbh, $host, $this->dbuser, $this->dbpassword, null, $port, $socket, $client_flags );
            } else {
               
// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
               
@mysqli_real_connect( $this->dbh, $host, $this->dbuser, $this->dbpassword, null, $port, $socket, $client_flags );
            }

            if (
$this->dbh->connect_errno ) {
               
$this->dbh = null;

               
/*
                 * It's possible ext/mysqli is misconfigured. Fall back to ext/mysql if:
                 *  - We haven't previously connected, and
                 *  - WP_USE_EXT_MYSQL isn't set to false, and
                 *  - ext/mysql is loaded.
                 */
               
$attempt_fallback = true;

                if (
$this->has_connected ) {
                   
$attempt_fallback = false;
                } elseif (
defined( 'WP_USE_EXT_MYSQL' ) && ! WP_USE_EXT_MYSQL ) {
                   
$attempt_fallback = false;
                } elseif ( !
function_exists( 'mysql_connect' ) ) {
                   
$attempt_fallback = false;
                }

                if (
$attempt_fallback ) {
                   
$this->use_mysqli = false;
                    return
$this->db_connect( $allow_bail );
                }
            }
        } else {
            if (
WP_DEBUG ) {
               
$this->dbh = mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, $new_link, $client_flags );
            } else {
               
// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
               
$this->dbh = @mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, $new_link, $client_flags );
            }
        }

        if ( !
$this->dbh && $allow_bail ) {
           
wp_load_translations_early();

           
// Load custom DB error template, if present.
           
if ( file_exists( WP_CONTENT_DIR . '/db-error.php' ) ) {
                require_once
WP_CONTENT_DIR . '/db-error.php';
                die();
            }

           
$message = '<h1>' . __( 'Error establishing a database connection' ) . "</h1>\n";

           
$message .= '<p>' . sprintf(
               
/* translators: 1: wp-config.php, 2: Database host. */
               
__( 'This either means that the username and password information in your %1$s file is incorrect or that contact with the database server at %2$s could not be established. This could mean your host&#8217;s database server is down.' ),
               
'<code>wp-config.php</code>',
               
'<code>' . htmlspecialchars( $this->dbhost, ENT_QUOTES ) . '</code>'
           
) . "</p>\n";

           
$message .= "<ul>\n";
           
$message .= '<li>' . __( 'Are you sure you have the correct username and password?' ) . "</li>\n";
           
$message .= '<li>' . __( 'Are you sure you have typed the correct hostname?' ) . "</li>\n";
           
$message .= '<li>' . __( 'Are you sure the database server is running?' ) . "</li>\n";
           
$message .= "</ul>\n";

           
$message .= '<p>' . sprintf(
               
/* translators: %s: Support forums URL. */
               
__( 'If you are unsure what these terms mean you should probably contact your host. If you still need help you can always visit the <a href="%s">WordPress Support Forums</a>.' ),
               
__( 'https://wordpress.org/support/forums/' )
            ) .
"</p>\n";

           
$this->bail( $message, 'db_connect_fail' );

            return
false;
        } elseif (
$this->dbh ) {
            if ( !
$this->has_connected ) {
               
$this->init_charset();
            }

           
$this->has_connected = true;

           
$this->set_charset( $this->dbh );

           
$this->ready = true;
           
$this->set_sql_mode();
           
$this->select( $this->dbname, $this->dbh );

            return
true;
        }

        return
false;
    }

   
/**
     * Parses the DB_HOST setting to interpret it for mysqli_real_connect().
     *
     * mysqli_real_connect() doesn't support the host param including a port or socket
     * like mysql_connect() does. This duplicates how mysql_connect() detects a port
     * and/or socket file.
     *
     * @since 4.9.0
     *
     * @param string $host The DB_HOST setting to parse.
     * @return array|false {
     *     Array containing the host, the port, the socket and
     *     whether it is an IPv6 address, in that order.
     *     False if the host couldn't be parsed.
     *
     *     @type string      $0 Host name.
     *     @type string|null $1 Port.
     *     @type string|null $2 Socket.
     *     @type bool        $3 Whether it is an IPv6 address.
     * }
     */
   
public function parse_db_host( $host ) {
       
$port    = null;
       
$socket  = null;
       
$is_ipv6 = false;

       
// First peel off the socket parameter from the right, if it exists.
       
$socket_pos = strpos( $host, ':/' );
        if (
false !== $socket_pos ) {
           
$socket = substr( $host, $socket_pos + 1 );
           
$host   = substr( $host, 0, $socket_pos );
        }

       
// We need to check for an IPv6 address first.
        // An IPv6 address will always contain at least two colons.
       
if ( substr_count( $host, ':' ) > 1 ) {
           
$pattern = '#^(?:\[)?(?P<host>[0-9a-fA-F:]+)(?:\]:(?P<port>[\d]+))?#';
           
$is_ipv6 = true;
        } else {
           
// We seem to be dealing with an IPv4 address.
           
$pattern = '#^(?P<host>[^:/]*)(?::(?P<port>[\d]+))?#';
        }

       
$matches = array();
       
$result  = preg_match( $pattern, $host, $matches );

        if (
1 !== $result ) {
           
// Couldn't parse the address, bail.
           
return false;
        }

       
$host = '';
        foreach ( array(
'host', 'port' ) as $component ) {
            if ( ! empty(
$matches[ $component ] ) ) {
                $
$component = $matches[ $component ];
            }
        }

        return array(
$host, $port, $socket, $is_ipv6 );
    }

   
/**
     * Checks that the connection to the database is still up. If not, try to reconnect.
     *
     * If this function is unable to reconnect, it will forcibly die, or if called
     * after the {@see 'template_redirect'} hook has been fired, return false instead.
     *
     * If `$allow_bail` is false, the lack of database connection will need to be handled manually.
     *
     * @since 3.9.0
     *
     * @param bool $allow_bail Optional. Allows the function to bail. Default true.
     * @return bool|void True if the connection is up.
     */
   
public function check_connection( $allow_bail = true ) {
        if (
$this->use_mysqli ) {
            if ( ! empty(
$this->dbh ) && mysqli_ping( $this->dbh ) ) {
                return
true;
            }
        } else {
            if ( ! empty(
$this->dbh ) && mysql_ping( $this->dbh ) ) {
                return
true;
            }
        }

       
$error_reporting = false;

       
// Disable warnings, as we don't want to see a multitude of "unable to connect" messages.
       
if ( WP_DEBUG ) {
           
$error_reporting = error_reporting();
           
error_reporting( $error_reporting & ~E_WARNING );
        }

        for (
$tries = 1; $tries <= $this->reconnect_retries; $tries++ ) {
           
// On the last try, re-enable warnings. We want to see a single instance
            // of the "unable to connect" message on the bail() screen, if it appears.
           
if ( $this->reconnect_retries === $tries && WP_DEBUG ) {
               
error_reporting( $error_reporting );
            }

            if (
$this->db_connect( false ) ) {
                if (
$error_reporting ) {
                   
error_reporting( $error_reporting );
                }

                return
true;
            }

           
sleep( 1 );
        }

       
// If template_redirect has already happened, it's too late for wp_die()/dead_db().
        // Let's just return and hope for the best.
       
if ( did_action( 'template_redirect' ) ) {
            return
false;
        }

        if ( !
$allow_bail ) {
            return
false;
        }

       
wp_load_translations_early();

       
$message = '<h1>' . __( 'Error reconnecting to the database' ) . "</h1>\n";

       
$message .= '<p>' . sprintf(
           
/* translators: %s: Database host. */
           
__( 'This means that the contact with the database server at %s was lost. This could mean your host&#8217;s database server is down.' ),
           
'<code>' . htmlspecialchars( $this->dbhost, ENT_QUOTES ) . '</code>'
       
) . "</p>\n";

       
$message .= "<ul>\n";
       
$message .= '<li>' . __( 'Are you sure the database server is running?' ) . "</li>\n";
       
$message .= '<li>' . __( 'Are you sure the database server is not under particularly heavy load?' ) . "</li>\n";
       
$message .= "</ul>\n";

       
$message .= '<p>' . sprintf(
           
/* translators: %s: Support forums URL. */
           
__( 'If you are unsure what these terms mean you should probably contact your host. If you still need help you can always visit the <a href="%s">WordPress Support Forums</a>.' ),
           
__( 'https://wordpress.org/support/forums/' )
        ) .
"</p>\n";

       
// We weren't able to reconnect, so we better bail.
       
$this->bail( $message, 'db_connect_fail' );

       
// Call dead_db() if bail didn't die, because this database is no more.
        // It has ceased to be (at least temporarily).
       
dead_db();
    }

   
/**
     * Performs a database query, using current database connection.
     *
     * More information can be found on the documentation page.
     *
     * @since 0.71
     *
     * @link https://developer.wordpress.org/reference/classes/wpdb/
     *
     * @param string $query Database query.
     * @return int|bool Boolean true for CREATE, ALTER, TRUNCATE and DROP queries. Number of rows
     *                  affected/selected for all other queries. Boolean false on error.
     */
   
public function query( $query ) {
        if ( !
$this->ready ) {
           
$this->check_current_query = true;
            return
false;
        }

       
/**
         * Filters the database query.
         *
         * Some queries are made before the plugins have been loaded,
         * and thus cannot be filtered with this method.
         *
         * @since 2.1.0
         *
         * @param string $query Database query.
         */
       
$query = apply_filters( 'query', $query );

        if ( !
$query ) {
           
$this->insert_id = 0;
            return
false;
        }

       
$this->flush();

       
// Log how the function was called.
       
$this->func_call = "\$db->query(\"$query\")";

       
// If we're writing to the database, make sure the query will write safely.
       
if ( $this->check_current_query && ! $this->check_ascii( $query ) ) {
           
$stripped_query = $this->strip_invalid_text_from_query( $query );
           
// strip_invalid_text_from_query() can perform queries, so we need
            // to flush again, just to make sure everything is clear.
           
$this->flush();
            if (
$stripped_query !== $query ) {
               
$this->insert_id  = 0;
               
$this->last_query = $query;

               
wp_load_translations_early();

               
$this->last_error = __( 'WordPress database error: Could not perform query because it contains invalid data.' );

                return
false;
            }
        }

       
$this->check_current_query = true;

       
// Keep track of the last query for debug.
       
$this->last_query = $query;

       
$this->_do_query( $query );

       
// Database server has gone away, try to reconnect.
       
$mysql_errno = 0;
        if ( ! empty(
$this->dbh ) ) {
            if (
$this->use_mysqli ) {
                if (
$this->dbh instanceof mysqli ) {
                   
$mysql_errno = mysqli_errno( $this->dbh );
                } else {
                   
// $dbh is defined, but isn't a real connection.
                    // Something has gone horribly wrong, let's try a reconnect.
                   
$mysql_errno = 2006;
                }
            } else {
                if (
is_resource( $this->dbh ) ) {
                   
$mysql_errno = mysql_errno( $this->dbh );
                } else {
                   
$mysql_errno = 2006;
                }
            }
        }

        if ( empty(
$this->dbh ) || 2006 === $mysql_errno ) {
            if (
$this->check_connection() ) {
               
$this->_do_query( $query );
            } else {
               
$this->insert_id = 0;
                return
false;
            }
        }

       
// If there is an error then take note of it.
       
if ( $this->use_mysqli ) {
            if (
$this->dbh instanceof mysqli ) {
               
$this->last_error = mysqli_error( $this->dbh );
            } else {
               
$this->last_error = __( 'Unable to retrieve the error message from MySQL' );
            }
        } else {
            if (
is_resource( $this->dbh ) ) {
               
$this->last_error = mysql_error( $this->dbh );
            } else {
               
$this->last_error = __( 'Unable to retrieve the error message from MySQL' );
            }
        }

        if (
$this->last_error ) {
           
// Clear insert_id on a subsequent failed insert.
           
if ( $this->insert_id && preg_match( '/^\s*(insert|replace)\s/i', $query ) ) {
               
$this->insert_id = 0;
            }

           
$this->print_error();
            return
false;
        }

        if (
preg_match( '/^\s*(create|alter|truncate|drop)\s/i', $query ) ) {
           
$return_val = $this->result;
        } elseif (
preg_match( '/^\s*(insert|delete|update|replace)\s/i', $query ) ) {
            if (
$this->use_mysqli ) {
               
$this->rows_affected = mysqli_affected_rows( $this->dbh );
            } else {
               
$this->rows_affected = mysql_affected_rows( $this->dbh );
            }
           
// Take note of the insert_id.
           
if ( preg_match( '/^\s*(insert|replace)\s/i', $query ) ) {
                if (
$this->use_mysqli ) {
                   
$this->insert_id = mysqli_insert_id( $this->dbh );
                } else {
                   
$this->insert_id = mysql_insert_id( $this->dbh );
                }
            }
           
// Return number of rows affected.
           
$return_val = $this->rows_affected;
        } else {
           
$num_rows = 0;
            if (
$this->use_mysqli && $this->result instanceof mysqli_result ) {
                while (
$row = mysqli_fetch_object( $this->result ) ) {
                   
$this->last_result[ $num_rows ] = $row;
                   
$num_rows++;
                }
            } elseif (
is_resource( $this->result ) ) {
                while (
$row = mysql_fetch_object( $this->result ) ) {
                   
$this->last_result[ $num_rows ] = $row;
                   
$num_rows++;
                }
            }

           
// Log and return the number of rows selected.
           
$this->num_rows = $num_rows;
           
$return_val     = $num_rows;
        }

        return
$return_val;
    }

   
/**
     * Internal function to perform the mysql_query() call.
     *
     * @since 3.9.0
     *
     * @see wpdb::query()
     *
     * @param string $query The query to run.
     */
   
private function _do_query( $query ) {
        if (
defined( 'SAVEQUERIES' ) && SAVEQUERIES ) {
           
$this->timer_start();
        }

        if ( ! empty(
$this->dbh ) && $this->use_mysqli ) {
           
$this->result = mysqli_query( $this->dbh, $query );
        } elseif ( ! empty(
$this->dbh ) ) {
           
$this->result = mysql_query( $query, $this->dbh );
        }
       
$this->num_queries++;

        if (
defined( 'SAVEQUERIES' ) && SAVEQUERIES ) {
           
$this->log_query(
               
$query,
               
$this->timer_stop(),
               
$this->get_caller(),
               
$this->time_start,
                array()
            );
        }
    }

   
/**
     * Logs query data.
     *
     * @since 5.3.0
     *
     * @param string $query           The query's SQL.
     * @param float  $query_time      Total time spent on the query, in seconds.
     * @param string $query_callstack Comma-separated list of the calling functions.
     * @param float  $query_start     Unix timestamp of the time at the start of the query.
     * @param array  $query_data      Custom query data.
     */
   
public function log_query( $query, $query_time, $query_callstack, $query_start, $query_data ) {
       
/**
         * Filters the custom data to log alongside a query.
         *
         * Caution should be used when modifying any of this data, it is recommended that any additional
         * information you need to store about a query be added as a new associative array element.
         *
         * @since 5.3.0
         *
         * @param array  $query_data      Custom query data.
         * @param string $query           The query's SQL.
         * @param float  $query_time      Total time spent on the query, in seconds.
         * @param string $query_callstack Comma-separated list of the calling functions.
         * @param float  $query_start     Unix timestamp of the time at the start of the query.
         */
       
$query_data = apply_filters( 'log_query_custom_data', $query_data, $query, $query_time, $query_callstack, $query_start );

       
$this->queries[] = array(
           
$query,
           
$query_time,
           
$query_callstack,
           
$query_start,
           
$query_data,
        );
    }

   
/**
     * Generates and returns a placeholder escape string for use in queries returned by ::prepare().
     *
     * @since 4.8.3
     *
     * @return string String to escape placeholders.
     */
   
public function placeholder_escape() {
        static
$placeholder;

        if ( !
$placeholder ) {
           
// If ext/hash is not present, compat.php's hash_hmac() does not support sha256.
           
$algo = function_exists( 'hash' ) ? 'sha256' : 'sha1';
           
// Old WP installs may not have AUTH_SALT defined.
           
$salt = defined( 'AUTH_SALT' ) && AUTH_SALT ? AUTH_SALT : (string) rand();

           
$placeholder = '{' . hash_hmac( $algo, uniqid( $salt, true ), $salt ) . '}';
        }

       
/*
         * Add the filter to remove the placeholder escaper. Uses priority 0, so that anything
         * else attached to this filter will receive the query with the placeholder string removed.
         */
       
if ( false === has_filter( 'query', array( $this, 'remove_placeholder_escape' ) ) ) {
           
add_filter( 'query', array( $this, 'remove_placeholder_escape' ), 0 );
        }

        return
$placeholder;
    }

   
/**
     * Adds a placeholder escape string, to escape anything that resembles a printf() placeholder.
     *
     * @since 4.8.3
     *
     * @param string $query The query to escape.
     * @return string The query with the placeholder escape string inserted where necessary.
     */
   
public function add_placeholder_escape( $query ) {
       
/*
         * To prevent returning anything that even vaguely resembles a placeholder,
         * we clobber every % we can find.
         */
       
return str_replace( '%', $this->placeholder_escape(), $query );
    }

   
/**
     * Removes the placeholder escape strings from a query.
     *
     * @since 4.8.3
     *
     * @param string $query The query from which the placeholder will be removed.
     * @return string The query with the placeholder removed.
     */
   
public function remove_placeholder_escape( $query ) {
        return
str_replace( $this->placeholder_escape(), '%', $query );
    }

   
/**
     * Inserts a row into the table.
     *
     * Examples:
     *
     *     wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
     *     wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
     *
     * @since 2.5.0
     *
     * @see wpdb::prepare()
     * @see wpdb::$field_types
     * @see wp_set_wpdb_vars()
     *
     * @param string       $table  Table name.
     * @param array        $data   Data to insert (in column => value pairs).
     *                             Both $data columns and $data values should be "raw" (neither should be SQL escaped).
     *                             Sending a null value will cause the column to be set to NULL - the corresponding
     *                             format is ignored in this case.
     * @param array|string $format Optional. An array of formats to be mapped to each of the value in $data.
     *                             If string, that format will be used for all of the values in $data.
     *                             A format is one of '%d', '%f', '%s' (integer, float, string).
     *                             If omitted, all values in $data will be treated as strings unless otherwise
     *                             specified in wpdb::$field_types.
     * @return int|false The number of rows inserted, or false on error.
     */
   
public function insert( $table, $data, $format = null ) {
        return
$this->_insert_replace_helper( $table, $data, $format, 'INSERT' );
    }

   
/**
     * Replaces a row in the table.
     *
     * Examples:
     *
     *     wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
     *     wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
     *
     * @since 3.0.0
     *
     * @see wpdb::prepare()
     * @see wpdb::$field_types
     * @see wp_set_wpdb_vars()
     *
     * @param string       $table  Table name.
     * @param array        $data   Data to insert (in column => value pairs).
     *                             Both $data columns and $data values should be "raw" (neither should be SQL escaped).
     *                             Sending a null value will cause the column to be set to NULL - the corresponding
     *                             format is ignored in this case.
     * @param array|string $format Optional. An array of formats to be mapped to each of the value in $data.
     *                             If string, that format will be used for all of the values in $data.
     *                             A format is one of '%d', '%f', '%s' (integer, float, string).
     *                             If omitted, all values in $data will be treated as strings unless otherwise
     *                             specified in wpdb::$field_types.
     * @return int|false The number of rows affected, or false on error.
     */
   
public function replace( $table, $data, $format = null ) {
        return
$this->_insert_replace_helper( $table, $data, $format, 'REPLACE' );
    }

   
/**
     * Helper function for insert and replace.
     *
     * Runs an insert or replace query based on $type argument.
     *
     * @since 3.0.0
     *
     * @see wpdb::prepare()
     * @see wpdb::$field_types
     * @see wp_set_wpdb_vars()
     *
     * @param string       $table  Table name.
     * @param array        $data   Data to insert (in column => value pairs).
     *                             Both $data columns and $data values should be "raw" (neither should be SQL escaped).
     *                             Sending a null value will cause the column to be set to NULL - the corresponding
     *                             format is ignored in this case.
     * @param array|string $format Optional. An array of formats to be mapped to each of the value in $data.
     *                             If string, that format will be used for all of the values in $data.
     *                             A format is one of '%d', '%f', '%s' (integer, float, string).
     *                             If omitted, all values in $data will be treated as strings unless otherwise
     *                             specified in wpdb::$field_types.
     * @param string       $type   Optional. Type of operation. Possible values include 'INSERT' or 'REPLACE'.
     *                             Default 'INSERT'.
     * @return int|false The number of rows affected, or false on error.
     */
   
public function _insert_replace_helper( $table, $data, $format = null, $type = 'INSERT' ) {
       
$this->insert_id = 0;

        if ( !
in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ), true ) ) {
            return
false;
        }

       
$data = $this->process_fields( $table, $data, $format );
        if (
false === $data ) {
            return
false;
        }

       
$formats = array();
       
$values  = array();
        foreach (
$data as $value ) {
            if (
is_null( $value['value'] ) ) {
               
$formats[] = 'NULL';
                continue;
            }

           
$formats[] = $value['format'];
           
$values[]  = $value['value'];
        }

       
$fields  = '`' . implode( '`, `', array_keys( $data ) ) . '`';
       
$formats = implode( ', ', $formats );

       
$sql = "$type INTO `$table` ($fields) VALUES ($formats)";

       
$this->check_current_query = false;
        return
$this->query( $this->prepare( $sql, $values ) );
    }

   
/**
     * Updates a row in the table.
     *
     * Examples:
     *
     *     wpdb::update( 'table', array( 'column' => 'foo', 'field' => 'bar' ), array( 'ID' => 1 ) )
     *     wpdb::update( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( 'ID' => 1 ), array( '%s', '%d' ), array( '%d' ) )
     *
     * @since 2.5.0
     *
     * @see wpdb::prepare()
     * @see wpdb::$field_types
     * @see wp_set_wpdb_vars()
     *
     * @param string       $table        Table name.
     * @param array        $data         Data to update (in column => value pairs).
     *                                   Both $data columns and $data values should be "raw" (neither should be SQL escaped).
     *                                   Sending a null value will cause the column to be set to NULL - the corresponding
     *                                   format is ignored in this case.
     * @param array        $where        A named array of WHERE clauses (in column => value pairs).
     *                                   Multiple clauses will be joined with ANDs.
     *                                   Both $where columns and $where values should be "raw".
     *                                   Sending a null value will create an IS NULL comparison - the corresponding
     *                                   format will be ignored in this case.
     * @param array|string $format       Optional. An array of formats to be mapped to each of the values in $data.
     *                                   If string, that format will be used for all of the values in $data.
     *                                   A format is one of '%d', '%f', '%s' (integer, float, string).
     *                                   If omitted, all values in $data will be treated as strings unless otherwise
     *                                   specified in wpdb::$field_types.
     * @param array|string $where_format Optional. An array of formats to be mapped to each of the values in $where.
     *                                   If string, that format will be used for all of the items in $where.
     *                                   A format is one of '%d', '%f', '%s' (integer, float, string).
     *                                   If omitted, all values in $where will be treated as strings.
     * @return int|false The number of rows updated, or false on error.
     */
   
public function update( $table, $data, $where, $format = null, $where_format = null ) {
        if ( !
is_array( $data ) || ! is_array( $where ) ) {
            return
false;
        }

       
$data = $this->process_fields( $table, $data, $format );
        if (
false === $data ) {
            return
false;
        }
       
$where = $this->process_fields( $table, $where, $where_format );
        if (
false === $where ) {
            return
false;
        }

       
$fields     = array();
       
$conditions = array();
       
$values     = array();
        foreach (
$data as $field => $value ) {
            if (
is_null( $value['value'] ) ) {
               
$fields[] = "`$field` = NULL";
                continue;
            }

           
$fields[] = "`$field` = " . $value['format'];
           
$values[] = $value['value'];
        }
        foreach (
$where as $field => $value ) {
            if (
is_null( $value['value'] ) ) {
               
$conditions[] = "`$field` IS NULL";
                continue;
            }

           
$conditions[] = "`$field` = " . $value['format'];
           
$values[]     = $value['value'];
        }

       
$fields     = implode( ', ', $fields );
       
$conditions = implode( ' AND ', $conditions );

       
$sql = "UPDATE `$table` SET $fields WHERE $conditions";

       
$this->check_current_query = false;
        return
$this->query( $this->prepare( $sql, $values ) );
    }

   
/**
     * Deletes a row in the table.
     *
     * Examples:
     *
     *     wpdb::delete( 'table', array( 'ID' => 1 ) )
     *     wpdb::delete( 'table', array( 'ID' => 1 ), array( '%d' ) )
     *
     * @since 3.4.0
     *
     * @see wpdb::prepare()
     * @see wpdb::$field_types
     * @see wp_set_wpdb_vars()
     *
     * @param string       $table        Table name.
     * @param array        $where        A named array of WHERE clauses (in column => value pairs).
     *                                   Multiple clauses will be joined with ANDs.
     *                                   Both $where columns and $where values should be "raw".
     *                                   Sending a null value will create an IS NULL comparison - the corresponding
     *                                   format will be ignored in this case.
     * @param array|string $where_format Optional. An array of formats to be mapped to each of the values in $where.
     *                                   If string, that format will be used for all of the items in $where.
     *                                   A format is one of '%d', '%f', '%s' (integer, float, string).
     *                                   If omitted, all values in $data will be treated as strings unless otherwise
     *                                   specified in wpdb::$field_types.
     * @return int|false The number of rows updated, or false on error.
     */
   
public function delete( $table, $where, $where_format = null ) {
        if ( !
is_array( $where ) ) {
            return
false;
        }

       
$where = $this->process_fields( $table, $where, $where_format );
        if (
false === $where ) {
            return
false;
        }

       
$conditions = array();
       
$values     = array();
        foreach (
$where as $field => $value ) {
            if (
is_null( $value['value'] ) ) {
               
$conditions[] = "`$field` IS NULL";
                continue;
            }

           
$conditions[] = "`$field` = " . $value['format'];
           
$values[]     = $value['value'];
        }

       
$conditions = implode( ' AND ', $conditions );

       
$sql = "DELETE FROM `$table` WHERE $conditions";

       
$this->check_current_query = false;
        return
$this->query( $this->prepare( $sql, $values ) );
    }

   
/**
     * Processes arrays of field/value pairs and field formats.
     *
     * This is a helper method for wpdb's CRUD methods, which take field/value pairs
     * for inserts, updates, and where clauses. This method first pairs each value
     * with a format. Then it determines the charset of that field, using that
     * to determine if any invalid text would be stripped. If text is stripped,
     * then field processing is rejected and the query fails.
     *
     * @since 4.2.0
     *
     * @param string $table  Table name.
     * @param array  $data   Field/value pair.
     * @param mixed  $format Format for each field.
     * @return array|false An array of fields that contain paired value and formats.
     *                     False for invalid values.
     */
   
protected function process_fields( $table, $data, $format ) {
       
$data = $this->process_field_formats( $data, $format );
        if (
false === $data ) {
            return
false;
        }

       
$data = $this->process_field_charsets( $data, $table );
        if (
false === $data ) {
            return
false;
        }

       
$data = $this->process_field_lengths( $data, $table );
        if (
false === $data ) {
            return
false;
        }

       
$converted_data = $this->strip_invalid_text( $data );

        if (
$data !== $converted_data ) {

           
$problem_fields = array();
            foreach (
$data as $field => $value ) {
                if (
$value !== $converted_data[ $field ] ) {
                   
$problem_fields[] = $field;
                }
            }

           
wp_load_translations_early();

            if (
1 === count( $problem_fields ) ) {
               
$this->last_error = sprintf(
                   
/* translators: %s: Database field where the error occurred. */
                   
__( 'WordPress database error: Processing the value for the following field failed: %s. The supplied value may be too long or contains invalid data.' ),
                   
reset( $problem_fields )
                );
            } else {
               
$this->last_error = sprintf(
                   
/* translators: %s: Database fields where the error occurred. */
                   
__( 'WordPress database error: Processing the values for the following fields failed: %s. The supplied values may be too long or contain invalid data.' ),
                   
implode( ', ', $problem_fields )
                );
            }

            return
false;
        }

        return
$data;
    }

   
/**
     * Prepares arrays of value/format pairs as passed to wpdb CRUD methods.
     *
     * @since 4.2.0
     *
     * @param array $data   Array of fields to values.
     * @param mixed $format Formats to be mapped to the values in $data.
     * @return array Array, keyed by field names with values being an array
     *               of 'value' and 'format' keys.
     */
   
protected function process_field_formats( $data, $format ) {
       
$formats          = (array) $format;
       
$original_formats = $formats;

        foreach (
$data as $field => $value ) {
           
$value = array(
               
'value'  => $value,
               
'format' => '%s',
            );

            if ( ! empty(
$format ) ) {
               
$value['format'] = array_shift( $formats );
                if ( !
$value['format'] ) {
                   
$value['format'] = reset( $original_formats );
                }
            } elseif ( isset(
$this->field_types[ $field ] ) ) {
               
$value['format'] = $this->field_types[ $field ];
            }

           
$data[ $field ] = $value;
        }

        return
$data;
    }

   
/**
     * Adds field charsets to field/value/format arrays generated by wpdb::process_field_formats().
     *
     * @since 4.2.0
     *
     * @param array  $data  As it comes from the wpdb::process_field_formats() method.
     * @param string $table Table name.
     * @return array|false The same array as $data with additional 'charset' keys.
     *                     False on failure.
     */
   
protected function process_field_charsets( $data, $table ) {
        foreach (
$data as $field => $value ) {
            if (
'%d' === $value['format'] || '%f' === $value['format'] ) {
               
/*
                 * We can skip this field if we know it isn't a string.
                 * This checks %d/%f versus ! %s because its sprintf() could take more.
                 */
               
$value['charset'] = false;
            } else {
               
$value['charset'] = $this->get_col_charset( $table, $field );
                if (
is_wp_error( $value['charset'] ) ) {
                    return
false;
                }
            }

           
$data[ $field ] = $value;
        }

        return
$data;
    }

   
/**
     * For string fields, records the maximum string length that field can safely save.
     *
     * @since 4.2.1
     *
     * @param array  $data  As it comes from the wpdb::process_field_charsets() method.
     * @param string $table Table name.
     * @return array|false The same array as $data with additional 'length' keys, or false if
     *                     any of the values were too long for their corresponding field.
     */
   
protected function process_field_lengths( $data, $table ) {
        foreach (
$data as $field => $value ) {
            if (
'%d' === $value['format'] || '%f' === $value['format'] ) {
               
/*
                 * We can skip this field if we know it isn't a string.
                 * This checks %d/%f versus ! %s because its sprintf() could take more.
                 */
               
$value['length'] = false;
            } else {
               
$value['length'] = $this->get_col_length( $table, $field );
                if (
is_wp_error( $value['length'] ) ) {
                    return
false;
                }
            }

           
$data[ $field ] = $value;
        }

        return
$data;
    }

   
/**
     * Retrieves one variable from the database.
     *
     * Executes a SQL query and returns the value from the SQL result.
     * If the SQL result contains more than one column and/or more than one row,
     * the value in the column and row specified is returned. If $query is null,
     * the value in the specified column and row from the previous SQL result is returned.
     *
     * @since 0.71
     *
     * @param string|null $query Optional. SQL query. Defaults to null, use the result from the previous query.
     * @param int         $x     Optional. Column of value to return. Indexed from 0.
     * @param int         $y     Optional. Row of value to return. Indexed from 0.
     * @return string|null Database query result (as string), or null on failure.
     */
   
public function get_var( $query = null, $x = 0, $y = 0 ) {
       
$this->func_call = "\$db->get_var(\"$query\", $x, $y)";

        if (
$query ) {
            if (
$this->check_current_query && $this->check_safe_collation( $query ) ) {
               
$this->check_current_query = false;
            }

           
$this->query( $query );
        }

       
// Extract var out of cached results based on x,y vals.
       
if ( ! empty( $this->last_result[ $y ] ) ) {
           
$values = array_values( get_object_vars( $this->last_result[ $y ] ) );
        }

       
// If there is a value return it, else return null.
       
return ( isset( $values[ $x ] ) && '' !== $values[ $x ] ) ? $values[ $x ] : null;
    }

   
/**
     * Retrieves one row from the database.
     *
     * Executes a SQL query and returns the row from the SQL result.
     *
     * @since 0.71
     *
     * @param string|null $query  SQL query.
     * @param string      $output Optional. The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which
     *                            correspond to an stdClass object, an associative array, or a numeric array,
     *                            respectively. Default OBJECT.
     * @param int         $y      Optional. Row to return. Indexed from 0.
     * @return array|object|null|void Database query result in format specified by $output or null on failure.
     */
   
public function get_row( $query = null, $output = OBJECT, $y = 0 ) {
       
$this->func_call = "\$db->get_row(\"$query\",$output,$y)";

        if (
$query ) {
            if (
$this->check_current_query && $this->check_safe_collation( $query ) ) {
               
$this->check_current_query = false;
            }

           
$this->query( $query );
        } else {
            return
null;
        }

        if ( ! isset(
$this->last_result[ $y ] ) ) {
            return
null;
        }

        if (
OBJECT === $output ) {
            return
$this->last_result[ $y ] ? $this->last_result[ $y ] : null;
        } elseif (
ARRAY_A === $output ) {
            return
$this->last_result[ $y ] ? get_object_vars( $this->last_result[ $y ] ) : null;
        } elseif (
ARRAY_N === $output ) {
            return
$this->last_result[ $y ] ? array_values( get_object_vars( $this->last_result[ $y ] ) ) : null;
        } elseif (
OBJECT === strtoupper( $output ) ) {
           
// Back compat for OBJECT being previously case-insensitive.
           
return $this->last_result[ $y ] ? $this->last_result[ $y ] : null;
        } else {
           
$this->print_error( ' $db->get_row(string query, output type, int offset) -- Output type must be one of: OBJECT, ARRAY_A, ARRAY_N' );
        }
    }

   
/**
     * Retrieves one column from the database.
     *
     * Executes a SQL query and returns the column from the SQL result.
     * If the SQL result contains more than one column, the column specified is returned.
     * If $query is null, the specified column from the previous SQL result is returned.
     *
     * @since 0.71
     *
     * @param string|null $query Optional. SQL query. Defaults to previous query.
     * @param int         $x     Optional. Column to return. Indexed from 0.
     * @return array Database query result. Array indexed from 0 by SQL result row number.
     */
   
public function get_col( $query = null, $x = 0 ) {
        if (
$query ) {
            if (
$this->check_current_query && $this->check_safe_collation( $query ) ) {
               
$this->check_current_query = false;
            }

           
$this->query( $query );
        }

       
$new_array = array();
       
// Extract the column values.
       
if ( $this->last_result ) {
            for (
$i = 0, $j = count( $this->last_result ); $i < $j; $i++ ) {
               
$new_array[ $i ] = $this->get_var( null, $x, $i );
            }
        }
        return
$new_array;
    }

   
/**
     * Retrieves an entire SQL result set from the database (i.e., many rows).
     *
     * Executes a SQL query and returns the entire SQL result.
     *
     * @since 0.71
     *
     * @param string $query  SQL query.
     * @param string $output Optional. Any of ARRAY_A | ARRAY_N | OBJECT | OBJECT_K constants.
     *                       With one of the first three, return an array of rows indexed
     *                       from 0 by SQL result row number. Each row is an associative array
     *                       (column => value, ...), a numerically indexed array (0 => value, ...),
     *                       or an object ( ->column = value ), respectively. With OBJECT_K,
     *                       return an associative array of row objects keyed by the value
     *                       of each row's first column's value. Duplicate keys are discarded.
     * @return array|object|null Database query results.
     */
   
public function get_results( $query = null, $output = OBJECT ) {
       
$this->func_call = "\$db->get_results(\"$query\", $output)";

        if (
$query ) {
            if (
$this->check_current_query && $this->check_safe_collation( $query ) ) {
               
$this->check_current_query = false;
            }

           
$this->query( $query );
        } else {
            return
null;
        }

       
$new_array = array();
        if (
OBJECT === $output ) {
           
// Return an integer-keyed array of row objects.
           
return $this->last_result;
        } elseif (
OBJECT_K === $output ) {
           
// Return an array of row objects with keys from column 1.
            // (Duplicates are discarded.)
           
if ( $this->last_result ) {
                foreach (
$this->last_result as $row ) {
                   
$var_by_ref = get_object_vars( $row );
                   
$key        = array_shift( $var_by_ref );
                    if ( ! isset(
$new_array[ $key ] ) ) {
                       
$new_array[ $key ] = $row;
                    }
                }
            }
            return
$new_array;
        } elseif (
ARRAY_A === $output || ARRAY_N === $output ) {
           
// Return an integer-keyed array of...
           
if ( $this->last_result ) {
                foreach ( (array)
$this->last_result as $row ) {
                    if (
ARRAY_N === $output ) {
                       
// ...integer-keyed row arrays.
                       
$new_array[] = array_values( get_object_vars( $row ) );
                    } else {
                       
// ...column name-keyed row arrays.
                       
$new_array[] = get_object_vars( $row );
                    }
                }
            }
            return
$new_array;
        } elseif (
strtoupper( $output ) === OBJECT ) {
           
// Back compat for OBJECT being previously case-insensitive.
           
return $this->last_result;
        }
        return
null;
    }

   
/**
     * Retrieves the character set for the given table.
     *
     * @since 4.2.0
     *
     * @param string $table Table name.
     * @return string|WP_Error Table character set, WP_Error object if it couldn't be found.
     */
   
protected function get_table_charset( $table ) {
       
$tablekey = strtolower( $table );

       
/**
         * Filters the table charset value before the DB is checked.
         *
         * Returning a non-null value from the filter will effectively short-circuit
         * checking the DB for the charset, returning that value instead.
         *
         * @since 4.2.0
         *
         * @param string|WP_Error|null $charset The character set to use, WP_Error object
         *                                      if it couldn't be found. Default null.
         * @param string               $table   The name of the table being checked.
         */
       
$charset = apply_filters( 'pre_get_table_charset', null, $table );
        if (
null !== $charset ) {
            return
$charset;
        }

        if ( isset(
$this->table_charset[ $tablekey ] ) ) {
            return
$this->table_charset[ $tablekey ];
        }

       
$charsets = array();
       
$columns  = array();

       
$table_parts = explode( '.', $table );
       
$table       = '`' . implode( '`.`', $table_parts ) . '`';
       
$results     = $this->get_results( "SHOW FULL COLUMNS FROM $table" );
        if ( !
$results ) {
            return new
WP_Error( 'wpdb_get_table_charset_failure', __( 'Could not retrieve table charset.' ) );
        }

        foreach (
$results as $column ) {
           
$columns[ strtolower( $column->Field ) ] = $column;
        }

       
$this->col_meta[ $tablekey ] = $columns;

        foreach (
$columns as $column ) {
            if ( ! empty(
$column->Collation ) ) {
                list(
$charset ) = explode( '_', $column->Collation );

               
// If the current connection can't support utf8mb4 characters, let's only send 3-byte utf8 characters.
               
if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
                   
$charset = 'utf8';
                }

               
$charsets[ strtolower( $charset ) ] = true;
            }

            list(
$type ) = explode( '(', $column->Type );

           
// A binary/blob means the whole query gets treated like this.
           
if ( in_array( strtoupper( $type ), array( 'BINARY', 'VARBINARY', 'TINYBLOB', 'MEDIUMBLOB', 'BLOB', 'LONGBLOB' ), true ) ) {
               
$this->table_charset[ $tablekey ] = 'binary';
                return
'binary';
            }
        }

       
// utf8mb3 is an alias for utf8.
       
if ( isset( $charsets['utf8mb3'] ) ) {
           
$charsets['utf8'] = true;
            unset(
$charsets['utf8mb3'] );
        }

       
// Check if we have more than one charset in play.
       
$count = count( $charsets );
        if (
1 === $count ) {
           
$charset = key( $charsets );
        } elseif (
0 === $count ) {
           
// No charsets, assume this table can store whatever.
           
$charset = false;
        } else {
           
// More than one charset. Remove latin1 if present and recalculate.
           
unset( $charsets['latin1'] );
           
$count = count( $charsets );
            if (
1 === $count ) {
               
// Only one charset (besides latin1).
               
$charset = key( $charsets );
            } elseif (
2 === $count && isset( $charsets['utf8'], $charsets['utf8mb4'] ) ) {
               
// Two charsets, but they're utf8 and utf8mb4, use utf8.
               
$charset = 'utf8';
            } else {
               
// Two mixed character sets. ascii.
               
$charset = 'ascii';
            }
        }

       
$this->table_charset[ $tablekey ] = $charset;
        return
$charset;
    }

   
/**
     * Retrieves the character set for the given column.
     *
     * @since 4.2.0
     *
     * @param string $table  Table name.
     * @param string $column Column name.
     * @return string|false|WP_Error Column character set as a string. False if the column has
     *                               no character set. WP_Error object if there was an error.
     */
   
public function get_col_charset( $table, $column ) {
       
$tablekey  = strtolower( $table );
       
$columnkey = strtolower( $column );

       
/**
         * Filters the column charset value before the DB is checked.
         *
         * Passing a non-null value to the filter will short-circuit
         * checking the DB for the charset, returning that value instead.
         *
         * @since 4.2.0
         *
         * @param string|null $charset The character set to use. Default null.
         * @param string      $table   The name of the table being checked.
         * @param string      $column  The name of the column being checked.
         */
       
$charset = apply_filters( 'pre_get_col_charset', null, $table, $column );
        if (
null !== $charset ) {
            return
$charset;
        }

       
// Skip this entirely if this isn't a MySQL database.
       
if ( empty( $this->is_mysql ) ) {
            return
false;
        }

        if ( empty(
$this->table_charset[ $tablekey ] ) ) {
           
// This primes column information for us.
           
$table_charset = $this->get_table_charset( $table );
            if (
is_wp_error( $table_charset ) ) {
                return
$table_charset;
            }
        }

       
// If still no column information, return the table charset.
       
if ( empty( $this->col_meta[ $tablekey ] ) ) {
            return
$this->table_charset[ $tablekey ];
        }

       
// If this column doesn't exist, return the table charset.
       
if ( empty( $this->col_meta[ $tablekey ][ $columnkey ] ) ) {
            return
$this->table_charset[ $tablekey ];
        }

       
// Return false when it's not a string column.
       
if ( empty( $this->col_meta[ $tablekey ][ $columnkey ]->Collation ) ) {
            return
false;
        }

        list(
$charset ) = explode( '_', $this->col_meta[ $tablekey ][ $columnkey ]->Collation );
        return
$charset;
    }

   
/**
     * Retrieves the maximum string length allowed in a given column.
     *
     * The length may either be specified as a byte length or a character length.
     *
     * @since 4.2.1
     *
     * @param string $table  Table name.
     * @param string $column Column name.
     * @return array|false|WP_Error {
     *     Array of column length information, false if the column has no length (for
     *     example, numeric column), WP_Error object if there was an error.
     *
     *     @type int    $length The column length.
     *     @type string $type   One of 'byte' or 'char'.
     */
   
public function get_col_length( $table, $column ) {
       
$tablekey  = strtolower( $table );
       
$columnkey = strtolower( $column );

       
// Skip this entirely if this isn't a MySQL database.
       
if ( empty( $this->is_mysql ) ) {
            return
false;
        }

        if ( empty(
$this->col_meta[ $tablekey ] ) ) {
           
// This primes column information for us.
           
$table_charset = $this->get_table_charset( $table );
            if (
is_wp_error( $table_charset ) ) {
                return
$table_charset;
            }
        }

        if ( empty(
$this->col_meta[ $tablekey ][ $columnkey ] ) ) {
            return
false;
        }

       
$typeinfo = explode( '(', $this->col_meta[ $tablekey ][ $columnkey ]->Type );

       
$type = strtolower( $typeinfo[0] );
        if ( ! empty(
$typeinfo[1] ) ) {
           
$length = trim( $typeinfo[1], ')' );
        } else {
           
$length = false;
        }

        switch (
$type ) {
            case
'char':
            case
'varchar':
                return array(
                   
'type'   => 'char',
                   
'length' => (int) $length,
                );

            case
'binary':
            case
'varbinary':
                return array(
                   
'type'   => 'byte',
                   
'length' => (int) $length,
                );

            case
'tinyblob':
            case
'tinytext':
                return array(
                   
'type'   => 'byte',
                   
'length' => 255,        // 2^8 - 1
               
);

            case
'blob':
            case
'text':
                return array(
                   
'type'   => 'byte',
                   
'length' => 65535,      // 2^16 - 1
               
);

            case
'mediumblob':
            case
'mediumtext':
                return array(
                   
'type'   => 'byte',
                   
'length' => 16777215,   // 2^24 - 1
               
);

            case
'longblob':
            case
'longtext':
                return array(
                   
'type'   => 'byte',
                   
'length' => 4294967295, // 2^32 - 1
               
);

            default:
                return
false;
        }
    }

   
/**
     * Checks if a string is ASCII.
     *
     * The negative regex is faster for non-ASCII strings, as it allows
     * the search to finish as soon as it encounters a non-ASCII character.
     *
     * @since 4.2.0
     *
     * @param string $string String to check.
     * @return bool True if ASCII, false if not.
     */
   
protected function check_ascii( $string ) {
        if (
function_exists( 'mb_check_encoding' ) ) {
            if (
mb_check_encoding( $string, 'ASCII' ) ) {
                return
true;
            }
        } elseif ( !
preg_match( '/[^\x00-\x7F]/', $string ) ) {
            return
true;
        }

        return
false;
    }

   
/**
     * Checks if the query is accessing a collation considered safe on the current version of MySQL.
     *
     * @since 4.2.0
     *
     * @param string $query The query to check.
     * @return bool True if the collation is safe, false if it isn't.
     */
   
protected function check_safe_collation( $query ) {
        if (
$this->checking_collation ) {
            return
true;
        }

       
// We don't need to check the collation for queries that don't read data.
       
$query = ltrim( $query, "\r\n\t (" );
        if (
preg_match( '/^(?:SHOW|DESCRIBE|DESC|EXPLAIN|CREATE)\s/i', $query ) ) {
            return
true;
        }

       
// All-ASCII queries don't need extra checking.
       
if ( $this->check_ascii( $query ) ) {
            return
true;
        }

       
$table = $this->get_table_from_query( $query );
        if ( !
$table ) {
            return
false;
        }

       
$this->checking_collation = true;
       
$collation                = $this->get_table_charset( $table );
       
$this->checking_collation = false;

       
// Tables with no collation, or latin1 only, don't need extra checking.
       
if ( false === $collation || 'latin1' === $collation ) {
            return
true;
        }

       
$table = strtolower( $table );
        if ( empty(
$this->col_meta[ $table ] ) ) {
            return
false;
        }

       
// If any of the columns don't have one of these collations, it needs more sanity checking.
       
foreach ( $this->col_meta[ $table ] as $col ) {
            if ( empty(
$col->Collation ) ) {
                continue;
            }

            if ( !
in_array( $col->Collation, array( 'utf8_general_ci', 'utf8_bin', 'utf8mb4_general_ci', 'utf8mb4_bin' ), true ) ) {
                return
false;
            }
        }

        return
true;
    }

   
/**
     * Strips any invalid characters based on value/charset pairs.
     *
     * @since 4.2.0
     *
     * @param array $data Array of value arrays. Each value array has the keys 'value' and 'charset'.
     *                    An optional 'ascii' key can be set to false to avoid redundant ASCII checks.
     * @return array|WP_Error The $data parameter, with invalid characters removed from each value.
     *                        This works as a passthrough: any additional keys such as 'field' are
     *                        retained in each value array. If we cannot remove invalid characters,
     *                        a WP_Error object is returned.
     */
   
protected function strip_invalid_text( $data ) {
       
$db_check_string = false;

        foreach (
$data as &$value ) {
           
$charset = $value['charset'];

            if (
is_array( $value['length'] ) ) {
               
$length                  = $value['length']['length'];
               
$truncate_by_byte_length = 'byte' === $value['length']['type'];
            } else {
               
$length = false;
               
// Since we have no length, we'll never truncate. Initialize the variable to false.
                // True would take us through an unnecessary (for this case) codepath below.
               
$truncate_by_byte_length = false;
            }

           
// There's no charset to work with.
           
if ( false === $charset ) {
                continue;
            }

           
// Column isn't a string.
           
if ( ! is_string( $value['value'] ) ) {
                continue;
            }

           
$needs_validation = true;
            if (
               
// latin1 can store any byte sequence.
               
'latin1' === $charset
           
||
               
// ASCII is always OK.
               
( ! isset( $value['ascii'] ) && $this->check_ascii( $value['value'] ) )
            ) {
               
$truncate_by_byte_length = true;
               
$needs_validation        = false;
            }

            if (
$truncate_by_byte_length ) {
               
mbstring_binary_safe_encoding();
                if (
false !== $length && strlen( $value['value'] ) > $length ) {
                   
$value['value'] = substr( $value['value'], 0, $length );
                }
               
reset_mbstring_encoding();

                if ( !
$needs_validation ) {
                    continue;
                }
            }

           
// utf8 can be handled by regex, which is a bunch faster than a DB lookup.
           
if ( ( 'utf8' === $charset || 'utf8mb3' === $charset || 'utf8mb4' === $charset ) && function_exists( 'mb_strlen' ) ) {
               
$regex = '/
                    (
                        (?: [\x00-\x7F]                  # single-byte sequences   0xxxxxxx
                        |   [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx
                        |   \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2
                        |   [\xE1-\xEC][\x80-\xBF]{2}
                        |   \xED[\x80-\x9F][\x80-\xBF]
                        |   [\xEE-\xEF][\x80-\xBF]{2}'
;

                if (
'utf8mb4' === $charset ) {
                   
$regex .= '
                        |    \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3
                        |    [\xF1-\xF3][\x80-\xBF]{3}
                        |    \xF4[\x80-\x8F][\x80-\xBF]{2}
                    '
;
                }

               
$regex         .= '){1,40}                          # ...one or more times
                    )
                    | .                                  # anything else
                    /x'
;
               
$value['value'] = preg_replace( $regex, '$1', $value['value'] );

                if (
false !== $length && mb_strlen( $value['value'], 'UTF-8' ) > $length ) {
                   
$value['value'] = mb_substr( $value['value'], 0, $length, 'UTF-8' );
                }
                continue;
            }

           
// We couldn't use any local conversions, send it to the DB.
           
$value['db']     = true;
           
$db_check_string = true;
        }
        unset(
$value ); // Remove by reference.

       
if ( $db_check_string ) {
           
$queries = array();
            foreach (
$data as $col => $value ) {
                if ( ! empty(
$value['db'] ) ) {
                   
// We're going to need to truncate by characters or bytes, depending on the length value we have.
                   
if ( isset( $value['length']['type'] ) && 'byte' === $value['length']['type'] ) {
                       
// Using binary causes LEFT() to truncate by bytes.
                       
$charset = 'binary';
                    } else {
                       
$charset = $value['charset'];
                    }

                    if (
$this->charset ) {
                       
$connection_charset = $this->charset;
                    } else {
                        if (
$this->use_mysqli ) {
                           
$connection_charset = mysqli_character_set_name( $this->dbh );
                        } else {
                           
$connection_charset = mysql_client_encoding();
                        }
                    }

                    if (
is_array( $value['length'] ) ) {
                       
$length          = sprintf( '%.0f', $value['length']['length'] );
                       
$queries[ $col ] = $this->prepare( "CONVERT( LEFT( CONVERT( %s USING $charset ), $length ) USING $connection_charset )", $value['value'] );
                    } elseif (
'binary' !== $charset ) {
                       
// If we don't have a length, there's no need to convert binary - it will always return the same result.
                       
$queries[ $col ] = $this->prepare( "CONVERT( CONVERT( %s USING $charset ) USING $connection_charset )", $value['value'] );
                    }

                    unset(
$data[ $col ]['db'] );
                }
            }

           
$sql = array();
            foreach (
$queries as $column => $query ) {
                if ( !
$query ) {
                    continue;
                }

               
$sql[] = $query . " AS x_$column";
            }

           
$this->check_current_query = false;
           
$row                       = $this->get_row( 'SELECT ' . implode( ', ', $sql ), ARRAY_A );
            if ( !
$row ) {
                return new
WP_Error( 'wpdb_strip_invalid_text_failure', __( 'Could not strip invalid text.' ) );
            }

            foreach (
array_keys( $data ) as $column ) {
                if ( isset(
$row[ "x_$column" ] ) ) {
                   
$data[ $column ]['value'] = $row[ "x_$column" ];
                }
            }
        }

        return
$data;
    }

   
/**
     * Strips any invalid characters from the query.
     *
     * @since 4.2.0
     *
     * @param string $query Query to convert.
     * @return string|WP_Error The converted query, or a WP_Error object if the conversion fails.
     */
   
protected function strip_invalid_text_from_query( $query ) {
       
// We don't need to check the collation for queries that don't read data.
       
$trimmed_query = ltrim( $query, "\r\n\t (" );
        if (
preg_match( '/^(?:SHOW|DESCRIBE|DESC|EXPLAIN|CREATE)\s/i', $trimmed_query ) ) {
            return
$query;
        }

       
$table = $this->get_table_from_query( $query );
        if (
$table ) {
           
$charset = $this->get_table_charset( $table );
            if (
is_wp_error( $charset ) ) {
                return
$charset;
            }

           
// We can't reliably strip text from tables containing binary/blob columns.
           
if ( 'binary' === $charset ) {
                return
$query;
            }
        } else {
           
$charset = $this->charset;
        }

       
$data = array(
           
'value'   => $query,
           
'charset' => $charset,
           
'ascii'   => false,
           
'length'  => false,
        );

       
$data = $this->strip_invalid_text( array( $data ) );
        if (
is_wp_error( $data ) ) {
            return
$data;
        }

        return
$data[0]['value'];
    }

   
/**
     * Strips any invalid characters from the string for a given table and column.
     *
     * @since 4.2.0
     *
     * @param string $table  Table name.
     * @param string $column Column name.
     * @param string $value  The text to check.
     * @return string|WP_Error The converted string, or a WP_Error object if the conversion fails.
     */
   
public function strip_invalid_text_for_column( $table, $column, $value ) {
        if ( !
is_string( $value ) ) {
            return
$value;
        }

       
$charset = $this->get_col_charset( $table, $column );
        if ( !
$charset ) {
           
// Not a string column.
           
return $value;
        } elseif (
is_wp_error( $charset ) ) {
           
// Bail on real errors.
           
return $charset;
        }

       
$data = array(
           
$column => array(
               
'value'   => $value,
               
'charset' => $charset,
               
'length'  => $this->get_col_length( $table, $column ),
            ),
        );

       
$data = $this->strip_invalid_text( $data );
        if (
is_wp_error( $data ) ) {
            return
$data;
        }

        return
$data[ $column ]['value'];
    }

   
/**
     * Finds the first table name referenced in a query.
     *
     * @since 4.2.0
     *
     * @param string $query The query to search.
     * @return string|false The table name found, or false if a table couldn't be found.
     */
   
protected function get_table_from_query( $query ) {
       
// Remove characters that can legally trail the table name.
       
$query = rtrim( $query, ';/-#' );

       
// Allow (select...) union [...] style queries. Use the first query's table name.
       
$query = ltrim( $query, "\r\n\t (" );

       
// Strip everything between parentheses except nested selects.
       
$query = preg_replace( '/\((?!\s*select)[^(]*?\)/is', '()', $query );

       
// Quickly match most common queries.
       
if ( preg_match(
           
'/^\s*(?:'
               
. 'SELECT.*?\s+FROM'
               
. '|INSERT(?:\s+LOW_PRIORITY|\s+DELAYED|\s+HIGH_PRIORITY)?(?:\s+IGNORE)?(?:\s+INTO)?'
               
. '|REPLACE(?:\s+LOW_PRIORITY|\s+DELAYED)?(?:\s+INTO)?'
               
. '|UPDATE(?:\s+LOW_PRIORITY)?(?:\s+IGNORE)?'
               
. '|DELETE(?:\s+LOW_PRIORITY|\s+QUICK|\s+IGNORE)*(?:.+?FROM)?'
           
. ')\s+((?:[0-9a-zA-Z$_.`-]|[\xC2-\xDF][\x80-\xBF])+)/is',
           
$query,
           
$maybe
       
) ) {
            return
str_replace( '`', '', $maybe[1] );
        }

       
// SHOW TABLE STATUS and SHOW TABLES WHERE Name = 'wp_posts'
       
if ( preg_match( '/^\s*SHOW\s+(?:TABLE\s+STATUS|(?:FULL\s+)?TABLES).+WHERE\s+Name\s*=\s*("|\')((?:[0-9a-zA-Z$_.-]|[\xC2-\xDF][\x80-\xBF])+)\\1/is', $query, $maybe ) ) {
            return
$maybe[2];
        }

       
/*
         * SHOW TABLE STATUS LIKE and SHOW TABLES LIKE 'wp\_123\_%'
         * This quoted LIKE operand seldom holds a full table name.
         * It is usually a pattern for matching a prefix so we just
         * strip the trailing % and unescape the _ to get 'wp_123_'
         * which drop-ins can use for routing these SQL statements.
         */
       
if ( preg_match( '/^\s*SHOW\s+(?:TABLE\s+STATUS|(?:FULL\s+)?TABLES)\s+(?:WHERE\s+Name\s+)?LIKE\s*("|\')((?:[\\\\0-9a-zA-Z$_.-]|[\xC2-\xDF][\x80-\xBF])+)%?\\1/is', $query, $maybe ) ) {
            return
str_replace( '\\_', '_', $maybe[2] );
        }

       
// Big pattern for the rest of the table-related queries.
       
if ( preg_match(
           
'/^\s*(?:'
               
. '(?:EXPLAIN\s+(?:EXTENDED\s+)?)?SELECT.*?\s+FROM'
               
. '|DESCRIBE|DESC|EXPLAIN|HANDLER'
               
. '|(?:LOCK|UNLOCK)\s+TABLE(?:S)?'
               
. '|(?:RENAME|OPTIMIZE|BACKUP|RESTORE|CHECK|CHECKSUM|ANALYZE|REPAIR).*\s+TABLE'
               
. '|TRUNCATE(?:\s+TABLE)?'
               
. '|CREATE(?:\s+TEMPORARY)?\s+TABLE(?:\s+IF\s+NOT\s+EXISTS)?'
               
. '|ALTER(?:\s+IGNORE)?\s+TABLE'
               
. '|DROP\s+TABLE(?:\s+IF\s+EXISTS)?'
               
. '|CREATE(?:\s+\w+)?\s+INDEX.*\s+ON'
               
. '|DROP\s+INDEX.*\s+ON'
               
. '|LOAD\s+DATA.*INFILE.*INTO\s+TABLE'
               
. '|(?:GRANT|REVOKE).*ON\s+TABLE'
               
. '|SHOW\s+(?:.*FROM|.*TABLE)'
           
. ')\s+\(*\s*((?:[0-9a-zA-Z$_.`-]|[\xC2-\xDF][\x80-\xBF])+)\s*\)*/is',
           
$query,
           
$maybe
       
) ) {
            return
str_replace( '`', '', $maybe[1] );
        }

        return
false;
    }

   
/**
     * Loads the column metadata from the last query.
     *
     * @since 3.5.0
     */
   
protected function load_col_info() {
        if (
$this->col_info ) {
            return;
        }

        if (
$this->use_mysqli ) {
           
$num_fields = mysqli_num_fields( $this->result );
            for (
$i = 0; $i < $num_fields; $i++ ) {
               
$this->col_info[ $i ] = mysqli_fetch_field( $this->result );
            }
        } else {
           
$num_fields = mysql_num_fields( $this->result );
            for (
$i = 0; $i < $num_fields; $i++ ) {
               
$this->col_info[ $i ] = mysql_fetch_field( $this->result, $i );
            }
        }
    }

   
/**
     * Retrieves column metadata from the last query.
     *
     * @since 0.71
     *
     * @param string $info_type  Optional. Possible values include 'name', 'table', 'def', 'max_length',
     *                           'not_null', 'primary_key', 'multiple_key', 'unique_key', 'numeric',
     *                           'blob', 'type', 'unsigned', 'zerofill'. Default 'name'.
     * @param int    $col_offset Optional. 0: col name. 1: which table the col's in. 2: col's max length.
     *                           3: if the col is numeric. 4: col's type. Default -1.
     * @return mixed Column results.
     */
   
public function get_col_info( $info_type = 'name', $col_offset = -1 ) {
       
$this->load_col_info();

        if (
$this->col_info ) {
            if ( -
1 === $col_offset ) {
               
$i         = 0;
               
$new_array = array();
                foreach ( (array)
$this->col_info as $col ) {
                   
$new_array[ $i ] = $col->{$info_type};
                   
$i++;
                }
                return
$new_array;
            } else {
                return
$this->col_info[ $col_offset ]->{$info_type};
            }
        }
    }

   
/**
     * Starts the timer, for debugging purposes.
     *
     * @since 1.5.0
     *
     * @return true
     */
   
public function timer_start() {
       
$this->time_start = microtime( true );
        return
true;
    }

   
/**
     * Stops the debugging timer.
     *
     * @since 1.5.0
     *
     * @return float Total time spent on the query, in seconds.
     */
   
public function timer_stop() {
        return (
microtime( true ) - $this->time_start );
    }

   
/**
     * Wraps errors in a nice header and footer and dies.
     *
     * Will not die if wpdb::$show_errors is false.
     *
     * @since 1.5.0
     *
     * @param string $message    The error message.
     * @param string $error_code Optional. A computer-readable string to identify the error.
     *                           Default '500'.
     * @return void|false Void if the showing of errors is enabled, false if disabled.
     */
   
public function bail( $message, $error_code = '500' ) {
        if (
$this->show_errors ) {
           
$error = '';

            if (
$this->use_mysqli ) {
                if (
$this->dbh instanceof mysqli ) {
                   
$error = mysqli_error( $this->dbh );
                } elseif (
mysqli_connect_errno() ) {
                   
$error = mysqli_connect_error();
                }
            } else {
                if (
is_resource( $this->dbh ) ) {
                   
$error = mysql_error( $this->dbh );
                } else {
                   
$error = mysql_error();
                }
            }

            if (
$error ) {
               
$message = '<p><code>' . $error . "</code></p>\n" . $message;
            }

           
wp_die( $message );
        } else {
            if (
class_exists( 'WP_Error', false ) ) {
               
$this->error = new WP_Error( $error_code, $message );
            } else {
               
$this->error = $message;
            }

            return
false;
        }
    }

   
/**
     * Closes the current database connection.
     *
     * @since 4.5.0
     *
     * @return bool True if the connection was successfully closed,
     *              false if it wasn't, or if the connection doesn't exist.
     */
   
public function close() {
        if ( !
$this->dbh ) {
            return
false;
        }

        if (
$this->use_mysqli ) {
           
$closed = mysqli_close( $this->dbh );
        } else {
           
$closed = mysql_close( $this->dbh );
        }

        if (
$closed ) {
           
$this->dbh           = null;
           
$this->ready         = false;
           
$this->has_connected = false;
        }

        return
$closed;
    }

   
/**
     * Determines whether MySQL database is at least the required minimum version.
     *
     * @since 2.5.0
     *
     * @global string $wp_version             The WordPress version string.
     * @global string $required_mysql_version The required MySQL version string.
     * @return void|WP_Error
     */
   
public function check_database_version() {
        global
$wp_version, $required_mysql_version;
       
// Make sure the server has the required MySQL version.
       
if ( version_compare( $this->db_version(), $required_mysql_version, '<' ) ) {
           
/* translators: 1: WordPress version number, 2: Minimum required MySQL version number. */
           
return new WP_Error( 'database_version', sprintf( __( '<strong>Error</strong>: WordPress %1$s requires MySQL %2$s or higher' ), $wp_version, $required_mysql_version ) );
        }
    }

   
/**
     * Determines whether the database supports collation.
     *
     * Called when WordPress is generating the table scheme.
     *
     * Use `wpdb::has_cap( 'collation' )`.
     *
     * @since 2.5.0
     * @deprecated 3.5.0 Use wpdb::has_cap()
     *
     * @return bool True if collation is supported, false if not.
     */
   
public function supports_collation() {
       
_deprecated_function( __FUNCTION__, '3.5.0', 'wpdb::has_cap( \'collation\' )' );
        return
$this->has_cap( 'collation' );
    }

   
/**
     * Retrieves the database character collate.
     *
     * @since 3.5.0
     *
     * @return string The database character collate.
     */
   
public function get_charset_collate() {
       
$charset_collate = '';

        if ( ! empty(
$this->charset ) ) {
           
$charset_collate = "DEFAULT CHARACTER SET $this->charset";
        }
        if ( ! empty(
$this->collate ) ) {
           
$charset_collate .= " COLLATE $this->collate";
        }

        return
$charset_collate;
    }

   
/**
     * Determines if a database supports a particular feature.
     *
     * @since 2.7.0
     * @since 4.1.0 Added support for the 'utf8mb4' feature.
     * @since 4.6.0 Added support for the 'utf8mb4_520' feature.
     *
     * @see wpdb::db_version()
     *
     * @param string $db_cap The feature to check for. Accepts 'collation', 'group_concat',
     *                       'subqueries', 'set_charset', 'utf8mb4', or 'utf8mb4_520'.
     * @return int|false Whether the database feature is supported, false otherwise.
     */
   
public function has_cap( $db_cap ) {
       
$version = $this->db_version();

        switch (
strtolower( $db_cap ) ) {
            case
'collation':    // @since 2.5.0
           
case 'group_concat': // @since 2.7.0
           
case 'subqueries':   // @since 2.7.0
               
return version_compare( $version, '4.1', '>=' );
            case
'set_charset':
                return
version_compare( $version, '5.0.7', '>=' );
            case
'utf8mb4':      // @since 4.1.0
               
if ( version_compare( $version, '5.5.3', '<' ) ) {
                    return
false;
                }
                if (
$this->use_mysqli ) {
                   
$client_version = mysqli_get_client_info();
                } else {
                   
$client_version = mysql_get_client_info();
                }

               
/*
                 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
                 * mysqlnd has supported utf8mb4 since 5.0.9.
                 */
               
if ( false !== strpos( $client_version, 'mysqlnd' ) ) {
                   
$client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $client_version );
                    return
version_compare( $client_version, '5.0.9', '>=' );
                } else {
                    return
version_compare( $client_version, '5.5.3', '>=' );
                }
            case
'utf8mb4_520': // @since 4.6.0
               
return version_compare( $version, '5.6', '>=' );
        }

        return
false;
    }

   
/**
     * Retrieves a comma-separated list of the names of the functions that called wpdb.
     *
     * @since 2.5.0
     *
     * @return string Comma-separated list of the calling functions.
     */
   
public function get_caller() {
        return
wp_debug_backtrace_summary( __CLASS__ );
    }

   
/**
     * Retrieves the database server version.
     *
     * @since 2.7.0
     *
     * @return string|null Version number on success, null on failure.
     */
   
public function db_version() {
        return
preg_replace( '/[^0-9.].*/', '', $this->db_server_info() );
    }

   
/**
     * Retrieves full database server information.
     *
     * @since 5.5.0
     *
     * @return string|false Server info on success, false on failure.
     */
   
public function db_server_info() {
        if (
$this->use_mysqli ) {
           
$server_info = mysqli_get_server_info( $this->dbh );
        } else {
           
$server_info = mysql_get_server_info( $this->dbh );
        }

        return
$server_info;
    }
}