/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 
 * 
 * @package WordPress 
 * @subpackage Database 
 * @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 
   * @access private 
   * @var bool 
   */ 
  var $show_errors = false; 
 
  /** 
   * Whether to suppress errors during the DB bootstrapping. 
   * 
   * @access private 
   * @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 
   * @access public 
   * @var int 
   */ 
  public $num_queries = 0; 
 
  /** 
   * Count of rows returned by previous query 
   * 
   * @since 0.71 
   * @access public 
   * @var int 
   */ 
  public $num_rows = 0; 
 
  /** 
   * Count of affected rows by previous query 
   * 
   * @since 0.71 
   * @access private 
   * @var int 
   */ 
  var $rows_affected = 0; 
 
  /** 
   * The ID generated for an AUTO_INCREMENT column by the previous query (usually INSERT). 
   * 
   * @since 0.71 
   * @access public 
   * @var int 
   */ 
  public $insert_id = 0; 
 
  /** 
   * Last query made 
   * 
   * @since 0.71 
   * @access private 
   * @var array 
   */ 
  var $last_query; 
 
  /** 
   * Results of the last query made 
   * 
   * @since 0.71 
   * @access private 
   * @var array|null 
   */ 
  var $last_result; 
 
  /** 
   * MySQL result, which is either a resource or boolean. 
   * 
   * @since 0.71 
   * @access protected 
   * @var mixed 
   */ 
  protected $result; 
 
  /** 
   * Cached column info, for sanity checking data before inserting 
   * 
   * @since 4.2.0 
   * @access protected 
   * @var array 
   */ 
  protected $col_meta = array(); 
 
  /** 
   * Calculated character sets on tables 
   * 
   * @since 4.2.0 
   * @access protected 
   * @var array 
   */ 
  protected $table_charset = array(); 
 
  /** 
   * Whether text fields in the current query need to be sanity checked. 
   * 
   * @since 4.2.0 
   * @access protected 
   * @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 
   * @access private 
   * @see wpdb::check_safe_collation() 
   * @var bool 
   */ 
  private $checking_collation = false; 
 
  /** 
   * Saved info on the table column 
   * 
   * @since 0.71 
   * @access protected 
   * @var array 
   */ 
  protected $col_info; 
 
  /** 
   * Saved queries that were executed 
   * 
   * @since 1.5.0 
   * @access private 
   * @var array 
   */ 
  var $queries; 
 
  /** 
   * The number of times to retry reconnecting before dying. 
   * 
   * @since 3.9.0 
   * @access protected 
   * @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 
   * @access public 
   * @var string 
   */ 
  public $prefix = ''; 
 
  /** 
   * WordPress base table prefix. 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
   public $base_prefix; 
 
  /** 
   * Whether the database queries are ready to start executing. 
   * 
   * @since 2.3.2 
   * @access private 
   * @var bool 
   */ 
  var $ready = false; 
 
  /** 
   * Blog ID. 
   * 
   * @since 3.0.0 
   * @access public 
   * @var int 
   */ 
  public $blogid = 0; 
 
  /** 
   * Site ID. 
   * 
   * @since 3.0.0 
   * @access public 
   * @var int 
   */ 
  public $siteid = 0; 
 
  /** 
   * List of WordPress per-blog tables 
   * 
   * @since 2.5.0 
   * @access private 
   * @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 
   * @access private 
   * @see wpdb::tables() 
   * @var array 
   */ 
  var $old_tables = array( 'categories', 'post2cat', 'link2cat' ); 
 
  /** 
   * List of WordPress global tables 
   * 
   * @since 3.0.0 
   * @access private 
   * @see wpdb::tables() 
   * @var array 
   */ 
  var $global_tables = array( 'users', 'usermeta' ); 
 
  /** 
   * List of Multisite global tables 
   * 
   * @since 3.0.0 
   * @access private 
   * @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 
   * @access public 
   * @var string 
   */ 
  public $comments; 
 
  /** 
   * WordPress Comment Metadata table 
   * 
   * @since 2.9.0 
   * @access public 
   * @var string 
   */ 
  public $commentmeta; 
 
  /** 
   * WordPress Links table 
   * 
   * @since 1.5.0 
   * @access public 
   * @var string 
   */ 
  public $links; 
 
  /** 
   * WordPress Options table 
   * 
   * @since 1.5.0 
   * @access public 
   * @var string 
   */ 
  public $options; 
 
  /** 
   * WordPress Post Metadata table 
   * 
   * @since 1.5.0 
   * @access public 
   * @var string 
   */ 
  public $postmeta; 
 
  /** 
   * WordPress Posts table 
   * 
   * @since 1.5.0 
   * @access public 
   * @var string 
   */ 
  public $posts; 
 
  /** 
   * WordPress Terms table 
   * 
   * @since 2.3.0 
   * @access public 
   * @var string 
   */ 
  public $terms; 
 
  /** 
   * WordPress Term Relationships table 
   * 
   * @since 2.3.0 
   * @access public 
   * @var string 
   */ 
  public $term_relationships; 
 
  /** 
   * WordPress Term Taxonomy table 
   * 
   * @since 2.3.0 
   * @access public 
   * @var string 
   */ 
  public $term_taxonomy; 
 
  /** 
   * WordPress Term Meta table. 
   * 
   * @since 4.4.0 
   * @access public 
   * @var string 
   */ 
  public $termmeta; 
 
  // 
  // Global and Multisite tables 
  // 
  
  /** 
   * WordPress User Metadata table 
   * 
   * @since 2.3.0 
   * @access public 
   * @var string 
   */ 
  public $usermeta; 
 
  /** 
   * WordPress Users table 
   * 
   * @since 1.5.0 
   * @access public 
   * @var string 
   */ 
  public $users; 
 
  /** 
   * Multisite Blogs table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $blogs; 
 
  /** 
   * Multisite Blog Versions table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $blog_versions; 
 
  /** 
   * Multisite Registration Log table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $registration_log; 
 
  /** 
   * Multisite Signups table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $signups; 
 
  /** 
   * Multisite Sites table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $site; 
 
  /** 
   * Multisite Sitewide Terms table 
   * 
   * @since 3.0.0 
   * @access public 
   * @var string 
   */ 
  public $sitecategories; 
 
  /** 
   * Multisite Site Metadata table 
   * 
   * @since 3.0.0 
   * @access public 
   * @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() 
   * @access public 
   * @var array 
   */ 
  public $field_types = array(); 
 
  /** 
   * Database table columns charset 
   * 
   * @since 2.2.0 
   * @access public 
   * @var string 
   */ 
  public $charset; 
 
  /** 
   * Database table columns collate 
   * 
   * @since 2.2.0 
   * @access public 
   * @var string 
   */ 
  public $collate; 
 
  /** 
   * Database Username 
   * 
   * @since 2.9.0 
   * @access protected 
   * @var string 
   */ 
  protected $dbuser; 
 
  /** 
   * Database Password 
   * 
   * @since 3.1.0 
   * @access protected 
   * @var string 
   */ 
  protected $dbpassword; 
 
  /** 
   * Database Name 
   * 
   * @since 3.1.0 
   * @access protected 
   * @var string 
   */ 
  protected $dbname; 
 
  /** 
   * Database Host 
   * 
   * @since 3.1.0 
   * @access protected 
   * @var string 
   */ 
  protected $dbhost; 
 
  /** 
   * Database Handle 
   * 
   * @since 0.71 
   * @access protected 
   * @var string 
   */ 
  protected $dbh; 
 
  /** 
   * A textual description of the last query/get_row/get_var call 
   * 
   * @since 3.0.0 
   * @access public 
   * @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 
   * @access public 
   * @var bool 
   */ 
  public $is_mysql = null; 
 
  /** 
   * A list of incompatible SQL modes. 
   * 
   * @since 3.9.0 
   * @access protected 
   * @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 
   * @access private 
   * @var bool 
   */ 
  private $use_mysqli = false; 
 
  /** 
   * Whether we've managed to successfully connect at some point 
   * 
   * @since 3.9.0 
   * @access private 
   * @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 and: 
       *  - WP_USE_EXT_MYSQL is defined as false, or 
       *  - We are a development version of WordPress, or 
       *  - We are running PHP 5.5 or greater, or 
       *  - ext/mysql is not loaded. 
       */ 
      if ( function_exists( 'mysqli_connect' ) ) { 
          if ( defined( 'WP_USE_EXT_MYSQL' ) ) { 
              $this->use_mysqli = ! WP_USE_EXT_MYSQL; 
          } elseif ( version_compare( phpversion(), '5.5', '>=' ) || ! function_exists( 'mysql_connect' ) ) { 
              $this->use_mysqli = true; 
          } elseif ( false !== strpos( $GLOBALS['wp_version'], '-' ) ) { 
              $this->use_mysqli = true; 
          } 
      } 
 
      $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 
   * @access public 
   * 
   * @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 
   * @access public 
   * 
   * @param int $blog_id 
   * @param int $site_id Optional. 
   * @return int previous blog id 
   */ 
  public function set_blog_id( $blog_id, $site_id = 0 ) { 
      if ( ! empty( $site_id ) ) 
          $this->siteid = $site_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’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’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() 
   * @access private 
   * 
   * @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 
   * @access private 
   * 
   * @param  string $string to escape 
   * @return string escaped 
   */ 
  function _real_escape( $string ) { 
      if ( $this->dbh ) { 
          if ( $this->use_mysqli ) { 
              return mysqli_real_escape_string( $this->dbh, $string ); 
          } else { 
              return mysql_real_escape_string( $string, $this->dbh ); 
          } 
      } 
 
      $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' ); 
      } 
      return addslashes( $string ); 
  } 
 
  /** 
   * Escape data. Works on arrays. 
   * 
   * @uses wpdb::_real_escape() 
   * @since  2.8.0 
   * @access public 
   * 
   * @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 directives can be used in the query format string: 
   *   %d (integer) 
   *   %f (float) 
   *   %s (string) 
   *   %% (literal percentage sign - no argument needed) 
   * 
   * All of %d, %f, and %s are to be left unquoted in the query string and they need an argument passed for them. 
   * Literals (%) as parts of the query must be properly written as %%. 
   * 
   * This function only supports a small subset of the sprintf syntax; it only supports %d (integer), %f (float), and %s (string). 
   * Does not support sign, padding, alignment, width or precision specifiers. 
   * Does not support argument numbering/swapping. 
   * 
   * May be called like {@link https://secure.php.net/sprintf sprintf()} or like {@link https://secure.php.net/vsprintf vsprintf()}. 
   * 
   * Both %d and %s should be left unquoted in the query string. 
   * 
   *     $wpdb->prepare( "SELECT * FROM `table` WHERE `column` = %s AND `field` = %d", 'foo', 1337 ); 
   *     $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 like 
   *                              {@link https://secure.php.net/vsprintf vsprintf()}, or the first variable to substitute into the query's placeholders if 
   *                              being called like {@link https://secure.php.net/sprintf sprintf()}. 
   * @param mixed       $args, ... further variables to substitute into the query's placeholders if being called like 
   *                              {@link https://secure.php.net/sprintf sprintf()}. 
   * @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 ) { 
          _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 
      if ( isset( $args[0] ) && is_array($args[0]) ) 
          $args = $args[0]; 
      $query = str_replace( "'%s'", '%s', $query ); // in case someone mistakenly already singlequoted it 
      $query = str_replace( '"%s"', '%s', $query ); // doublequote unquoting 
      $query = preg_replace( '|(?<!%)%f|' , '%F', $query ); // Force floats to be locale unaware 
      $query = preg_replace( '|(?<!%)%s|', "'%s'", $query ); // quote the strings, avoiding escaped strings like %%s 
      array_walk( $args, array( $this, 'escape_by_ref' ) ); 
      return @vsprintf( $query, $args ); 
  } 
 
  /** 
   * 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 
   * @access public 
   * 
   * @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(); 
 
          // 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. 
          $port = null; 
          $socket = null; 
          $host = $this->dbhost; 
          $port_or_socket = strstr( $host, ':' ); 
          if ( ! empty( $port_or_socket ) ) { 
              $host = substr( $host, 0, strpos( $host, ':' ) ); 
              $port_or_socket = substr( $port_or_socket, 1 ); 
              if ( 0 !== strpos( $port_or_socket, '/' ) ) { 
                  $port = intval( $port_or_socket ); 
                  $maybe_socket = strstr( $port_or_socket, ':' ); 
                  if ( ! empty( $maybe_socket ) ) { 
                      $socket = substr( $maybe_socket, 1 ); 
                  } 
              } else { 
                  $socket = $port_or_socket; 
              } 
          } 
 
          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’t contact the database server at %2$s. This could mean your host’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’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; 
  } 
 
  /** 
   * 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’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’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 
   * 
   * @access private 
   * @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() ); 
      } 
  } 
 
  /** 
   * 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 $type argument. 
   * 
   * @access private 
   * @since 3.0.0 
   * @see wpdb::prepare() 
   * @see wpdb::$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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access public 
   * 
   * @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 
   * @access public 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * @access protected 
   * 
   * @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'] ) ) { 
                      $queries[ $col ] = $this->prepare( "CONVERT( LEFT( CONVERT( %s USING $charset ), %.0f ) USING $connection_charset )", $value['value'], $value['length']['length'] ); 
                  } 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 
   * @access protected 
   * 
   * @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 
   * @access public 
   * 
   * @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 
   * @access protected 
   * 
   * @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 
   * 
   * @access protected 
   */ 
  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 
   * @access public 
   * 
   * @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',  
   *                       or 'utf8mb4'. 
   * @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 ); 
  } 
}