/old/wp-includes/wp-db.php

<?php


/**


 * WordPress DB 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' );


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 Object


 *


 * 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://codex.wordpress.org/Function_Reference/wpdb_Class


 *


 * @since 0.71


 */


class wpdb {





	/**


	 * Whether to show SQL/DB errors.


	 *


	 * Default behavior is to show errors if both WP_DEBUG and WP_DEBUG_DISPLAY


	 * evaluated to true.


	 *


	 * @since 0.71


	 * @var bool


	 */


	var $show_errors = false;





	/**


	 * Whether to suppress errors during the DB bootstrapping.


	 *


	 * @since 2.5.0


	 * @var bool


	 */


	var $suppress_errors = false;





	/**


	 * The last error during query.


	 *


	 * @since 2.5.0


	 * @var string


	 */


	public $last_error = '';





	/**


	 * Amount of queries made


	 *


	 * @since 1.2.0


	 * @var int


	 */


	public $num_queries = 0;





	/**


	 * Count of rows returned by previous query


	 *


	 * @since 0.71


	 * @var int


	 */


	public $num_rows = 0;





	/**


	 * Count of affected rows by previous query


	 *


	 * @since 0.71


	 * @var int


	 */


	var $rows_affected = 0;





	/**


	 * The ID generated for an AUTO_INCREMENT column by the previous query (usually INSERT).


	 *


	 * @since 0.71


	 * @var int


	 */


	public $insert_id = 0;





	/**


	 * Last query made


	 *


	 * @since 0.71


	 * @var array


	 */


	var $last_query;





	/**


	 * Results of the last query made


	 *


	 * @since 0.71


	 * @var array|null


	 */


	var $last_result;





	/**


	 * MySQL result, which is either a resource or boolean.


	 *


	 * @since 0.71


	 * @var mixed


	 */


	protected $result;





	/**


	 * Cached column info, for sanity checking data before inserting


	 *


	 * @since 4.2.0


	 * @var array


	 */


	protected $col_meta = array();





	/**


	 * Calculated character sets on tables


	 *


	 * @since 4.2.0


	 * @var array


	 */


	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;





	/**


	 * Saved queries that were executed


	 *


	 * @since 1.5.0


	 * @var array


	 */


	var $queries;





	/**


	 * The number of times to retry reconnecting before dying.


	 *


	 * @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


	 */


	var $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-blog tables


	 *


	 * @since 2.5.0


	 * @see wpdb::tables()


	 * @var array


	 */


	var $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 array


	 */


	var $old_tables = array( 'categories', 'post2cat', 'link2cat' );





	/**


	 * List of WordPress global tables


	 *


	 * @since 3.0.0


	 * @see wpdb::tables()


	 * @var array


	 */


	var $global_tables = array( 'users', 'usermeta' );





	/**


	 * List of Multisite global tables


	 *


	 * @since 3.0.0


	 * @see wpdb::tables()


	 * @var array


	 */


	var $ms_global_tables = array( 'blogs', 'signups', 'site', 'sitemeta',


		'sitecategories', 'registration_log', 'blog_versions' );





	/**


	 * 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 Versions table


	 *


	 * @since 3.0.0


	 * @var string


	 */


	public $blog_versions;





	/**


	 * 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


	 *


	 * @since 0.71


	 * @var string


	 */


	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 array


	 */


	protected $incompatible_modes = array( 'NO_ZERO_DATE', 'ONLY_FULL_GROUP_BY',


		'STRICT_TRANS_TABLES', 'STRICT_ALL_TABLES', 'TRADITIONAL' );





	/**


	 * Whether to use mysqli over mysql.


	 *


	 * @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;





	/**


	 * Connects to the database server and selects a database


	 *


	 * PHP5 style constructor for compatibility with PHP5. Does


	 * the actual setting up of the class properties and connection


	 * to the database.


	 *


	 * @link https://core.trac.wordpress.org/ticket/3354


	 * @since 2.0.8


	 *


	 * @global string $wp_version


	 *


	 * @param string $dbuser     MySQL database user


	 * @param string $dbpassword MySQL database password


	 * @param string $dbname     MySQL database name


	 * @param string $dbhost     MySQL database host


	 */


	public function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {


		register_shutdown_function( array( $this, '__destruct' ) );





		if ( WP_DEBUG && WP_DEBUG_DISPLAY )


			$this->show_errors();





		// Use ext/mysqli 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();


	}





	/**


	 * PHP5 style destructor and will run when database object is destroyed.


	 *


	 * @see wpdb::__construct()


	 * @since 2.0.8


	 * @return true


	 */


	public function __destruct() {


		return true;


	}





	/**


	 * 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 );


	}





	/**


	 * Set $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.


	 */


	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 resource $dbh     The resource given by 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 );


				}


			}


		}


	}





	/**


	 * Change the current SQL mode, and ensure 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.


	 */


	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 ) ) {


				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.


	 * @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 if running 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. Can be all, global, ms_global, blog, or old tables. Defaults to all.


	 * @param bool   $prefix  Optional. Whether to include table prefixes. Default true. If blog


	 *                        prefix is requested, then the custom users and usermeta tables will be mapped.


	 * @param int    $blog_id Optional. The blog_id to prefix. Defaults to wpdb::$blogid. Used only when prefix is requested.


	 * @return array 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 ) )


					$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 database connection.


	 *


	 * The database name will be changed based on the current database


	 * connection. On failure, the execution will bail and display an DB error.


	 *


	 * @since 0.71


	 *


	 * @param string        $db  MySQL database name


	 * @param resource|null $dbh Optional link identifier.


	 */


	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/' )


				) . "</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


	 */


	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()


	 *


	 * @see mysqli_real_escape_string()


	 * @see mysql_real_escape_string()


	 * @since 2.8.0


	 *


	 * @param  string $string to escape


	 * @return string escaped


	 */


	function _real_escape( $string ) {


		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 );


			if ( function_exists( '__' ) ) {


				/* 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' );


			} else {


				_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 );


	}





	/**


	 * Escape data. Works on arrays.


	 *


	 * @uses wpdb::_real_escape()


	 * @since  2.8.0


	 *


	 * @param  string|array $data


	 * @return string|array escaped


	 */


	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 mixed $data


	 * @return mixed


	 */


	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 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.


	 *


	 * 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 for your usage.


	 *


	 * 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 {@see 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' );


	 *


	 * @link https://secure.php.net/sprintf Description of syntax.


	 * @since 2.3.0


	 *


	 * @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 wih 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( __( 'The query argument of %s must have a placeholder.' ), 'wpdb::prepare()' ), '3.9.0' );


		}





		$args = func_get_args();


		array_shift( $args );





		// If args were passed as an array (as in vsprintf), move them up.


		$passed_as_array = false;


		if ( is_array( $args[0] ) && count( $args ) == 1 ) {


			$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( __( '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 backwards 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 );





		if ( count( $args ) !== $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',


					/* translators: 1: number of placeholders, 2: number of arguments passed */


					sprintf( __( 'The query does not contain the correct number of placeholders (%1$d) for the number of arguments passed (%2$d).' ),


						$placeholders,


						count( $args ) ),


					'4.8.3'


				);


			}


		}





		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 MySQL.


	 *


	 * 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 real_escape next.


	 */


	public function esc_like( $text ) {


		return addcslashes( $text, '_%\\' );


	}





	/**


	 * Print 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 false|void False if the showing of errors is 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();





		if ( $caller = $this->get_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 of errors. However,


	 * this function can be used to enable and disable showing of database


	 * errors.


	 *


	 * @since 0.71


	 * @see wpdb::hide_errors()


	 *


	 * @param bool $show Whether to show or hide errors


	 * @return bool Old value for showing errors.


	 */


	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 active


	 */


	public function hide_errors() {


		$show = $this->show_errors;


		$this->show_errors = false;


		return $show;


	}





	/**


	 * Whether to suppress database errors.


	 *


	 * By default database errors are suppressed, with a simple


	 * call to this function they can be enabled.


	 *


	 * @since 2.5.0


	 * @see wpdb::hide_errors()


	 * @param bool $suppress Optional. New value. Defaults to true.


	 * @return bool Old value


	 */


	public function suppress_errors( $suppress = true ) {


		$errors = $this->suppress_errors;


		$this->suppress_errors = (bool) $suppress;


		return $errors;


	}





	/**


	 * Kill cached query results.


	 *


	 * @since 0.71


	 */


	public function flush() {


		$this->last_result = array();


		$this->col_info    = null;


		$this->last_query  = null;


		$this->rows_affected = $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 );


		}


	}





	/**


	 * Connect to and select 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 ) {


			$this->dbh = mysqli_init();





			$host    = $this->dbhost;


			$port    = null;


			$socket  = null;


			$is_ipv6 = false;





			if ( $host_data = $this->parse_db_host( $this->dbhost ) ) {


				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 {


				@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 {


				$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 that you have typed the correct hostname?' ) . "</li>\n";


			$message .= '<li>' . __( 'Are you sure that 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/' )


			) . "</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;


	}





	/**


	 * Parse 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|bool Array containing the host, the port, the socket and whether


	 *                    it is an IPv6 address, in that order. If $host couldn't be parsed,


	 *                    returns false.


	 */


	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 ( $socket_pos !== false ) {


			$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 after the


	 * 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 that the database server is running?' ) . "</li>\n";


		$message .= '<li>' . __( 'Are you sure that 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 host. If you still need help you can always visit the <a href="%s">WordPress Support Forums</a>.' ),


			__( 'https://wordpress.org/support/' )


		) . "</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();


	}





	/**


	 * Perform a MySQL database query, using current database connection.


	 *


	 * More information can be found on the codex page.


	 *


	 * @since 0.71


	 *


	 * @param string $query Database query


	 * @return int|false Number of rows affected/selected or 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 );





		$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;


				return false;


			}


		}





		$this->check_current_query = true;





		// Keep track of the last query for debug.


		$this->last_query = $query;





		$this->_do_query( $query );





		// MySQL 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 number of rows the query returned


			// and return 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->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );


		}


	}





	/**


	 * 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 recieve the query with the placeholder string removed.


		 */


		if ( ! 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 );


	}





	/**


	 * Insert a row into a table.


	 *


	 *     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' );


	}





	/**


	 * Replace a row into a table.


	 *


	 *     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. What type of operation is this? INSERT or REPLACE. Defaults to INSERT.


	 * @return int|false The number of rows affected, or false on error.


	 */


	function _insert_replace_helper( $table, $data, $format = null, $type = 'INSERT' ) {


		$this->insert_id = 0;





		if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) ) {


			return false;


		}





		$data = $this->process_fields( $table, $data, $format );


		if ( false === $data ) {


			return false;


		}





		$formats = $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 ) );


	}





	/**


	 * Update a row in the table


	 *


	 *     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 = $conditions = $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 ) );


	}





	/**


	 * Delete a row in the table


	 *


	 *     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 $where will be treated as strings unless otherwise specified in wpdb::$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 = $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 Returns an array of fields that contain paired values


	 *                    and formats. Returns 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 ) {


			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 = $original_formats = (array) $format;





		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


	 * the wpdb::process_field_formats() method.


	 *


	 * @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.


	 */


	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, record 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;


	}





	/**


	 * Retrieve 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, this function returns the value in the column and row specified.


	 * If $query is null, this function returns the value in the specified column and row from the previous SQL result.


	 *


	 * @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 ( $this->check_current_query && $this->check_safe_collation( $query ) ) {


			$this->check_current_query = false;


		}





		if ( $query ) {


			$this->query( $query );


		}





		// Extract var out of cached results based 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;


	}





	/**


	 * Retrieve 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 ( $this->check_current_query && $this->check_safe_collation( $query ) ) {


			$this->check_current_query = false;


		}





		if ( $query ) {


			$this->query( $query );


		} else {


			return null;


		}





		if ( !isset( $this->last_result[$y] ) )


			return null;





		if ( $output == OBJECT ) {


			return $this->last_result[$y] ? $this->last_result[$y] : null;


		} elseif ( $output == ARRAY_A ) {


			return $this->last_result[$y] ? get_object_vars( $this->last_result[$y] ) : null;


		} elseif ( $output == ARRAY_N ) {


			return $this->last_result[$y] ? array_values( get_object_vars( $this->last_result[$y] ) ) : null;


		} elseif ( strtoupper( $output ) === OBJECT ) {


			// 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" );


		}


	}





	/**


	 * Retrieve 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, this function returns the column specified.


	 * If $query is null, this function returns the specified column from the previous SQL result.


	 *


	 * @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 ( $this->check_current_query && $this->check_safe_collation( $query ) ) {


			$this->check_current_query = false;


		}





		if ( $query ) {


			$this->query( $query );


		}





		$new_array = array();


		// Extract the column values


		for ( $i = 0, $j = count( $this->last_result ); $i < $j; $i++ ) {


			$new_array[$i] = $this->get_var( null, $x, $i );


		}


		return $new_array;


	}





	/**


	 * Retrieve 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 ( $this->check_current_query && $this->check_safe_collation( $query ) ) {


			$this->check_current_query = false;


		}





		if ( $query ) {


			$this->query( $query );


		} else {


			return null;


		}





		$new_array = array();


		if ( $output == OBJECT ) {


			// Return an integer-keyed array of row objects


			return $this->last_result;


		} elseif ( $output == OBJECT_K ) {


			// Return an array of row objects with keys from column 1


			// (Duplicates are discarded)


			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 ( $output == ARRAY_A || $output == ARRAY_N ) {


			// Return an integer-keyed array of...


			if ( $this->last_result ) {


				foreach ( (array) $this->last_result as $row ) {


					if ( $output == ARRAY_N ) {


						// ...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.


		 *


		 * Passing a non-null value to the filter will effectively short-circuit


		 * checking the DB for the charset, returning that value instead.


		 *


		 * @since 4.2.0


		 *


		 * @param string $charset The character set to use. 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 = $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' );


		}





		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' ) ) ) {


				$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 $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;


	}





	/**


	 * Retrieve 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( 'length' => (int), 'type' => 'byte' | 'char' )


	 *                              false if the column has no length (for example, numeric column)


	 *                              WP_Error object if there was an error.


	 */


	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;


		}


	}





	/**


	 * Check 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;


	}





	/**


	 * Check 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'] = $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 ( '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'] );


					} else if ( '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' );


			}





			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'];


	}





	/**


	 * Find the first table name referenced in a query.


	 *


	 * @since 4.2.0


	 *


	 * @param string $query The query to search.


	 * @return string|false $table 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;


	}





	/**


	 * Load 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 );


			}


		}


	}





	/**


	 * Retrieve column metadata from the last query.


	 *


	 * @since 0.71


	 *


	 * @param string $info_type  Optional. Type one of name, table, def, max_length, not_null, primary_key, multiple_key, unique_key, numeric, blob, type, unsigned, zerofill


	 * @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


	 * @return mixed Column Results


	 */


	public function get_col_info( $info_type = 'name', $col_offset = -1 ) {


		$this->load_col_info();





		if ( $this->col_info ) {


			if ( $col_offset == -1 ) {


				$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.


	 * @return false|void


	 */


	public function bail( $message, $error_code = '500' ) {


		if ( !$this->show_errors ) {


			if ( class_exists( 'WP_Error', false ) ) {


				$this->error = new WP_Error($error_code, $message);


			} else {


				$this->error = $message;


			}


			return false;


		}


		wp_die($message);


	}








	/**


	 * Closes the current database connection.


	 *


	 * @since 4.5.0


	 *


	 * @return bool True if the connection was successfully closed, false if it wasn't,


	 *              or 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;


	}





	/**


	 * Whether MySQL database is at least the required minimum version.


	 *


	 * @since 2.5.0


	 *


	 * @global string $wp_version


	 * @global string $required_mysql_version


	 *


	 * @return WP_Error|void


	 */


	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 ));


		}


	}





	/**


	 * 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 version does not


	 */


	public function supports_collation() {


		_deprecated_function( __FUNCTION__, '3.5.0', 'wpdb::has_cap( \'collation\' )' );


		return $this->has_cap( 'collation' );


	}





	/**


	 * 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;


	}





	/**


	 * Determine 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;


	}





	/**


	 * Retrieve the name of the function that called wpdb.


	 *


	 * Searches up the list of functions until it reaches


	 * the one that would most logically had called this method.


	 *


	 * @since 2.5.0


	 *


	 * @return string|array The name of the calling function


	 */


	public function get_caller() {


		return wp_debug_backtrace_summary( __CLASS__ );


	}





	/**


	 * Retrieves the MySQL server version.


	 *


	 * @since 2.7.0


	 *


	 * @return null|string Null on failure, version number on success.


	 */


	public function db_version() {


		if ( $this->use_mysqli ) {


			$server_info = mysqli_get_server_info( $this->dbh );


		} else {


			$server_info = mysql_get_server_info( $this->dbh );


		}


		return preg_replace( '/[^0-9.].*/', '', $server_info );


	}


}