<?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>' . __( 'Can&#8217;t select database' ) . "</h1>\n";

				$message .= '<p>' . sprintf(
					/* translators: %s: Database name. */
					__( 'We were able to connect to the database server (which means your username and password is okay) but not able to select the %s database.' ),
					'<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 don&#8217;t 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 we can&#8217;t contact the database server at %2$s. 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&#8217;re 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 $host couldn't be parsed.
	 */
	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 we lost contact with the database server at %s. 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&#8217;re unsure what these terms mean you should probably contact your h…