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/wp-includes/wp-db.php

https://bitbucket.org/abnopanda/wordpress
PHP | 1737 lines | 604 code | 180 blank | 953 comment | 121 complexity | aa2abecd280b19547f1106db62f0ef30 MD5 | raw file
   1<?php
   2/**
   3 * WordPress DB Class
   4 *
   5 * Original code from {@link http://php.justinvincent.com Justin Vincent (justin@visunet.ie)}
   6 *
   7 * @package WordPress
   8 * @subpackage Database
   9 * @since 0.71
  10 */
  11
  12/**
  13 * @since 0.71
  14 */
  15define( 'EZSQL_VERSION', 'WP1.25' );
  16
  17/**
  18 * @since 0.71
  19 */
  20define( 'OBJECT', 'OBJECT', true );
  21
  22/**
  23 * @since 2.5.0
  24 */
  25define( 'OBJECT_K', 'OBJECT_K' );
  26
  27/**
  28 * @since 0.71
  29 */
  30define( 'ARRAY_A', 'ARRAY_A' );
  31
  32/**
  33 * @since 0.71
  34 */
  35define( 'ARRAY_N', 'ARRAY_N' );
  36
  37/**
  38 * WordPress Database Access Abstraction Object
  39 *
  40 * It is possible to replace this class with your own
  41 * by setting the $wpdb global variable in wp-content/db.php
  42 * file to your class. The wpdb class will still be included,
  43 * so you can extend it or simply use your own.
  44 *
  45 * @link http://codex.wordpress.org/Function_Reference/wpdb_Class
  46 *
  47 * @package WordPress
  48 * @subpackage Database
  49 * @since 0.71
  50 */
  51class wpdb {
  52
  53	/**
  54	 * Whether to show SQL/DB errors
  55	 *
  56	 * @since 0.71
  57	 * @access private
  58	 * @var bool
  59	 */
  60	var $show_errors = false;
  61
  62	/**
  63	 * Whether to suppress errors during the DB bootstrapping.
  64	 *
  65	 * @access private
  66	 * @since 2.5.0
  67	 * @var bool
  68	 */
  69	var $suppress_errors = false;
  70
  71	/**
  72	 * The last error during query.
  73	 *
  74	 * @since 2.5.0
  75	 * @var string
  76	 */
  77	var $last_error = '';
  78
  79	/**
  80	 * Amount of queries made
  81	 *
  82	 * @since 1.2.0
  83	 * @access private
  84	 * @var int
  85	 */
  86	var $num_queries = 0;
  87
  88	/**
  89	 * Count of rows returned by previous query
  90	 *
  91	 * @since 0.71
  92	 * @access private
  93	 * @var int
  94	 */
  95	var $num_rows = 0;
  96
  97	/**
  98	 * Count of affected rows by previous query
  99	 *
 100	 * @since 0.71
 101	 * @access private
 102	 * @var int
 103	 */
 104	var $rows_affected = 0;
 105
 106	/**
 107	 * The ID generated for an AUTO_INCREMENT column by the previous query (usually INSERT).
 108	 *
 109	 * @since 0.71
 110	 * @access public
 111	 * @var int
 112	 */
 113	var $insert_id = 0;
 114
 115	/**
 116	 * Last query made
 117	 *
 118	 * @since 0.71
 119	 * @access private
 120	 * @var array
 121	 */
 122	var $last_query;
 123
 124	/**
 125	 * Results of the last query made
 126	 *
 127	 * @since 0.71
 128	 * @access private
 129	 * @var array|null
 130	 */
 131	var $last_result;
 132
 133	/**
 134	 * MySQL result, which is either a resource or boolean.
 135	 *
 136	 * @since 0.71
 137	 * @access protected
 138	 * @var mixed
 139	 */
 140	protected $result;
 141
 142	/**
 143	 * Saved info on the table column
 144	 *
 145	 * @since 0.71
 146	 * @access protected
 147	 * @var array
 148	 */
 149	protected $col_info;
 150
 151	/**
 152	 * Saved queries that were executed
 153	 *
 154	 * @since 1.5.0
 155	 * @access private
 156	 * @var array
 157	 */
 158	var $queries;
 159
 160	/**
 161	 * WordPress table prefix
 162	 *
 163	 * You can set this to have multiple WordPress installations
 164	 * in a single database. The second reason is for possible
 165	 * security precautions.
 166	 *
 167	 * @since 2.5.0
 168	 * @access private
 169	 * @var string
 170	 */
 171	var $prefix = '';
 172
 173	/**
 174	 * Whether the database queries are ready to start executing.
 175	 *
 176	 * @since 2.3.2
 177	 * @access private
 178	 * @var bool
 179	 */
 180	var $ready = false;
 181
 182	/**
 183	 * {@internal Missing Description}}
 184	 *
 185	 * @since 3.0.0
 186	 * @access public
 187	 * @var int
 188	 */
 189	var $blogid = 0;
 190
 191	/**
 192	 * {@internal Missing Description}}
 193	 *
 194	 * @since 3.0.0
 195	 * @access public
 196	 * @var int
 197	 */
 198	var $siteid = 0;
 199
 200	/**
 201	 * List of WordPress per-blog tables
 202	 *
 203	 * @since 2.5.0
 204	 * @access private
 205	 * @see wpdb::tables()
 206	 * @var array
 207	 */
 208	var $tables = array( 'posts', 'comments', 'links', 'options', 'postmeta',
 209		'terms', 'term_taxonomy', 'term_relationships', 'commentmeta' );
 210
 211	/**
 212	 * List of deprecated WordPress tables
 213	 *
 214	 * categories, post2cat, and link2cat were deprecated in 2.3.0, db version 5539
 215	 *
 216	 * @since 2.9.0
 217	 * @access private
 218	 * @see wpdb::tables()
 219	 * @var array
 220	 */
 221	var $old_tables = array( 'categories', 'post2cat', 'link2cat' );
 222
 223	/**
 224	 * List of WordPress global tables
 225	 *
 226	 * @since 3.0.0
 227	 * @access private
 228	 * @see wpdb::tables()
 229	 * @var array
 230	 */
 231	var $global_tables = array( 'users', 'usermeta' );
 232
 233	/**
 234	 * List of Multisite global tables
 235	 *
 236	 * @since 3.0.0
 237	 * @access private
 238	 * @see wpdb::tables()
 239	 * @var array
 240	 */
 241	var $ms_global_tables = array( 'blogs', 'signups', 'site', 'sitemeta',
 242		'sitecategories', 'registration_log', 'blog_versions' );
 243
 244	/**
 245	 * WordPress Comments table
 246	 *
 247	 * @since 1.5.0
 248	 * @access public
 249	 * @var string
 250	 */
 251	var $comments;
 252
 253	/**
 254	 * WordPress Comment Metadata table
 255	 *
 256	 * @since 2.9.0
 257	 * @access public
 258	 * @var string
 259	 */
 260	var $commentmeta;
 261
 262	/**
 263	 * WordPress Links table
 264	 *
 265	 * @since 1.5.0
 266	 * @access public
 267	 * @var string
 268	 */
 269	var $links;
 270
 271	/**
 272	 * WordPress Options table
 273	 *
 274	 * @since 1.5.0
 275	 * @access public
 276	 * @var string
 277	 */
 278	var $options;
 279
 280	/**
 281	 * WordPress Post Metadata table
 282	 *
 283	 * @since 1.5.0
 284	 * @access public
 285	 * @var string
 286	 */
 287	var $postmeta;
 288
 289	/**
 290	 * WordPress Posts table
 291	 *
 292	 * @since 1.5.0
 293	 * @access public
 294	 * @var string
 295	 */
 296	var $posts;
 297
 298	/**
 299	 * WordPress Terms table
 300	 *
 301	 * @since 2.3.0
 302	 * @access public
 303	 * @var string
 304	 */
 305	var $terms;
 306
 307	/**
 308	 * WordPress Term Relationships table
 309	 *
 310	 * @since 2.3.0
 311	 * @access public
 312	 * @var string
 313	 */
 314	var $term_relationships;
 315
 316	/**
 317	 * WordPress Term Taxonomy table
 318	 *
 319	 * @since 2.3.0
 320	 * @access public
 321	 * @var string
 322	 */
 323	var $term_taxonomy;
 324
 325	/*
 326	 * Global and Multisite tables
 327	 */
 328
 329	/**
 330	 * WordPress User Metadata table
 331	 *
 332	 * @since 2.3.0
 333	 * @access public
 334	 * @var string
 335	 */
 336	var $usermeta;
 337
 338	/**
 339	 * WordPress Users table
 340	 *
 341	 * @since 1.5.0
 342	 * @access public
 343	 * @var string
 344	 */
 345	var $users;
 346
 347	/**
 348	 * Multisite Blogs table
 349	 *
 350	 * @since 3.0.0
 351	 * @access public
 352	 * @var string
 353	 */
 354	var $blogs;
 355
 356	/**
 357	 * Multisite Blog Versions table
 358	 *
 359	 * @since 3.0.0
 360	 * @access public
 361	 * @var string
 362	 */
 363	var $blog_versions;
 364
 365	/**
 366	 * Multisite Registration Log table
 367	 *
 368	 * @since 3.0.0
 369	 * @access public
 370	 * @var string
 371	 */
 372	var $registration_log;
 373
 374	/**
 375	 * Multisite Signups table
 376	 *
 377	 * @since 3.0.0
 378	 * @access public
 379	 * @var string
 380	 */
 381	var $signups;
 382
 383	/**
 384	 * Multisite Sites table
 385	 *
 386	 * @since 3.0.0
 387	 * @access public
 388	 * @var string
 389	 */
 390	var $site;
 391
 392	/**
 393	 * Multisite Sitewide Terms table
 394	 *
 395	 * @since 3.0.0
 396	 * @access public
 397	 * @var string
 398	 */
 399	var $sitecategories;
 400
 401	/**
 402	 * Multisite Site Metadata table
 403	 *
 404	 * @since 3.0.0
 405	 * @access public
 406	 * @var string
 407	 */
 408	var $sitemeta;
 409
 410	/**
 411	 * Format specifiers for DB columns. Columns not listed here default to %s. Initialized during WP load.
 412	 *
 413	 * Keys are column names, values are format types: 'ID' => '%d'
 414	 *
 415	 * @since 2.8.0
 416	 * @see wpdb::prepare()
 417	 * @see wpdb::insert()
 418	 * @see wpdb::update()
 419	 * @see wpdb::delete()
 420	 * @see wp_set_wpdb_vars()
 421	 * @access public
 422	 * @var array
 423	 */
 424	var $field_types = array();
 425
 426	/**
 427	 * Database table columns charset
 428	 *
 429	 * @since 2.2.0
 430	 * @access public
 431	 * @var string
 432	 */
 433	var $charset;
 434
 435	/**
 436	 * Database table columns collate
 437	 *
 438	 * @since 2.2.0
 439	 * @access public
 440	 * @var string
 441	 */
 442	var $collate;
 443
 444	/**
 445	 * Whether to use mysql_real_escape_string
 446	 *
 447	 * @since 2.8.0
 448	 * @access public
 449	 * @var bool
 450	 */
 451	var $real_escape = false;
 452
 453	/**
 454	 * Database Username
 455	 *
 456	 * @since 2.9.0
 457	 * @access protected
 458	 * @var string
 459	 */
 460	protected $dbuser;
 461
 462	/**
 463	 * Database Password
 464	 *
 465	 * @since 3.1.0
 466	 * @access protected
 467	 * @var string
 468	 */
 469	protected $dbpassword;
 470
 471	/**
 472	 * Database Name
 473	 *
 474	 * @since 3.1.0
 475	 * @access protected
 476	 * @var string
 477	 */
 478	protected $dbname;
 479
 480	/**
 481	 * Database Host
 482	 *
 483	 * @since 3.1.0
 484	 * @access protected
 485	 * @var string
 486	 */
 487	protected $dbhost;
 488
 489	/**
 490	 * Database Handle
 491	 *
 492	 * @since 0.71
 493	 * @access protected
 494	 * @var string
 495	 */
 496	protected $dbh;
 497
 498	/**
 499	 * A textual description of the last query/get_row/get_var call
 500	 *
 501	 * @since 3.0.0
 502	 * @access public
 503	 * @var string
 504	 */
 505	var $func_call;
 506
 507	/**
 508	 * Whether MySQL is used as the database engine.
 509	 *
 510	 * Set in WPDB::db_connect() to true, by default. This is used when checking
 511	 * against the required MySQL version for WordPress. Normally, a replacement
 512	 * database drop-in (db.php) will skip these checks, but setting this to true
 513	 * will force the checks to occur.
 514	 *
 515	 * @since 3.3.0
 516	 * @access public
 517	 * @var bool
 518	 */
 519	public $is_mysql = null;
 520
 521	/**
 522	 * Connects to the database server and selects a database
 523	 *
 524	 * PHP5 style constructor for compatibility with PHP5. Does
 525	 * the actual setting up of the class properties and connection
 526	 * to the database.
 527	 *
 528	 * @link http://core.trac.wordpress.org/ticket/3354
 529	 * @since 2.0.8
 530	 *
 531	 * @param string $dbuser MySQL database user
 532	 * @param string $dbpassword MySQL database password
 533	 * @param string $dbname MySQL database name
 534	 * @param string $dbhost MySQL database host
 535	 */
 536	function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {
 537		register_shutdown_function( array( $this, '__destruct' ) );
 538
 539		if ( WP_DEBUG )
 540			$this->show_errors();
 541
 542		$this->init_charset();
 543
 544		$this->dbuser = $dbuser;
 545		$this->dbpassword = $dbpassword;
 546		$this->dbname = $dbname;
 547		$this->dbhost = $dbhost;
 548
 549		$this->db_connect();
 550	}
 551
 552	/**
 553	 * PHP5 style destructor and will run when database object is destroyed.
 554	 *
 555	 * @see wpdb::__construct()
 556	 * @since 2.0.8
 557	 * @return bool true
 558	 */
 559	function __destruct() {
 560		return true;
 561	}
 562
 563	/**
 564	 * PHP5 style magic getter, used to lazy-load expensive data.
 565	 *
 566	 * @since 3.5.0
 567	 *
 568	 * @param string $name The private member to get, and optionally process
 569	 * @return mixed The private member
 570	 */
 571	function __get( $name ) {
 572		if ( 'col_info' == $name )
 573			$this->load_col_info();
 574
 575		return $this->$name;
 576	}
 577
 578	/**
 579	 * Magic function, for backwards compatibility
 580	 *
 581	 * @since 3.5.0
 582	 *
 583	 * @param string $name  The private member to set
 584	 * @param mixed  $value The value to set
 585	 */
 586	function __set( $name, $value ) {
 587		$this->$name = $value;
 588	}
 589
 590	/**
 591	 * Magic function, for backwards compatibility
 592	 *
 593	 * @since 3.5.0
 594	 *
 595	 * @param string $name  The private member to check
 596	 *
 597	 * @return bool If the member is set or not
 598	 */
 599	function __isset( $name ) {
 600		return isset( $this->$name );
 601	}
 602
 603	/**
 604	 * Magic function, for backwards compatibility
 605	 *
 606	 * @since 3.5.0
 607	 *
 608	 * @param string $name  The private member to unset
 609	 */
 610	function __unset( $name ) {
 611		unset( $this->$name );
 612	}
 613
 614	/**
 615	 * Set $this->charset and $this->collate
 616	 *
 617	 * @since 3.1.0
 618	 */
 619	function init_charset() {
 620		if ( function_exists('is_multisite') && is_multisite() ) {
 621			$this->charset = 'utf8';
 622			if ( defined( 'DB_COLLATE' ) && DB_COLLATE )
 623				$this->collate = DB_COLLATE;
 624			else
 625				$this->collate = 'utf8_general_ci';
 626		} elseif ( defined( 'DB_COLLATE' ) ) {
 627			$this->collate = DB_COLLATE;
 628		}
 629
 630		if ( defined( 'DB_CHARSET' ) )
 631			$this->charset = DB_CHARSET;
 632	}
 633
 634	/**
 635	 * Sets the connection's character set.
 636	 *
 637	 * @since 3.1.0
 638	 *
 639	 * @param resource $dbh     The resource given by mysql_connect
 640	 * @param string   $charset The character set (optional)
 641	 * @param string   $collate The collation (optional)
 642	 */
 643	function set_charset($dbh, $charset = null, $collate = null) {
 644		if ( !isset($charset) )
 645			$charset = $this->charset;
 646		if ( !isset($collate) )
 647			$collate = $this->collate;
 648		if ( $this->has_cap( 'collation', $dbh ) && !empty( $charset ) ) {
 649			if ( function_exists( 'mysql_set_charset' ) && $this->has_cap( 'set_charset', $dbh ) ) {
 650				mysql_set_charset( $charset, $dbh );
 651				$this->real_escape = true;
 652			} else {
 653				$query = $this->prepare( 'SET NAMES %s', $charset );
 654				if ( ! empty( $collate ) )
 655					$query .= $this->prepare( ' COLLATE %s', $collate );
 656				mysql_query( $query, $dbh );
 657			}
 658		}
 659	}
 660
 661	/**
 662	 * Sets the table prefix for the WordPress tables.
 663	 *
 664	 * @since 2.5.0
 665	 *
 666	 * @param string $prefix Alphanumeric name for the new prefix.
 667	 * @param bool $set_table_names Optional. Whether the table names, e.g. wpdb::$posts, should be updated or not.
 668	 * @return string|WP_Error Old prefix or WP_Error on error
 669	 */
 670	function set_prefix( $prefix, $set_table_names = true ) {
 671
 672		if ( preg_match( '|[^a-z0-9_]|i', $prefix ) )
 673			return new WP_Error('invalid_db_prefix', 'Invalid database prefix' );
 674
 675		$old_prefix = is_multisite() ? '' : $prefix;
 676
 677		if ( isset( $this->base_prefix ) )
 678			$old_prefix = $this->base_prefix;
 679
 680		$this->base_prefix = $prefix;
 681
 682		if ( $set_table_names ) {
 683			foreach ( $this->tables( 'global' ) as $table => $prefixed_table )
 684				$this->$table = $prefixed_table;
 685
 686			if ( is_multisite() && empty( $this->blogid ) )
 687				return $old_prefix;
 688
 689			$this->prefix = $this->get_blog_prefix();
 690
 691			foreach ( $this->tables( 'blog' ) as $table => $prefixed_table )
 692				$this->$table = $prefixed_table;
 693
 694			foreach ( $this->tables( 'old' ) as $table => $prefixed_table )
 695				$this->$table = $prefixed_table;
 696		}
 697		return $old_prefix;
 698	}
 699
 700	/**
 701	 * Sets blog id.
 702	 *
 703	 * @since 3.0.0
 704	 * @access public
 705	 * @param int $blog_id
 706	 * @param int $site_id Optional.
 707	 * @return string previous blog id
 708	 */
 709	function set_blog_id( $blog_id, $site_id = 0 ) {
 710		if ( ! empty( $site_id ) )
 711			$this->siteid = $site_id;
 712
 713		$old_blog_id  = $this->blogid;
 714		$this->blogid = $blog_id;
 715
 716		$this->prefix = $this->get_blog_prefix();
 717
 718		foreach ( $this->tables( 'blog' ) as $table => $prefixed_table )
 719			$this->$table = $prefixed_table;
 720
 721		foreach ( $this->tables( 'old' ) as $table => $prefixed_table )
 722			$this->$table = $prefixed_table;
 723
 724		return $old_blog_id;
 725	}
 726
 727	/**
 728	 * Gets blog prefix.
 729	 *
 730	 * @uses is_multisite()
 731	 * @since 3.0.0
 732	 * @param int $blog_id Optional.
 733	 * @return string Blog prefix.
 734	 */
 735	function get_blog_prefix( $blog_id = null ) {
 736		if ( is_multisite() ) {
 737			if ( null === $blog_id )
 738				$blog_id = $this->blogid;
 739			$blog_id = (int) $blog_id;
 740			if ( defined( 'MULTISITE' ) && ( 0 == $blog_id || 1 == $blog_id ) )
 741				return $this->base_prefix;
 742			else
 743				return $this->base_prefix . $blog_id . '_';
 744		} else {
 745			return $this->base_prefix;
 746		}
 747	}
 748
 749	/**
 750	 * Returns an array of WordPress tables.
 751	 *
 752	 * Also allows for the CUSTOM_USER_TABLE and CUSTOM_USER_META_TABLE to
 753	 * override the WordPress users and usermeta tables that would otherwise
 754	 * be determined by the prefix.
 755	 *
 756	 * The scope argument can take one of the following:
 757	 *
 758	 * 'all' - returns 'all' and 'global' tables. No old tables are returned.
 759	 * 'blog' - returns the blog-level tables for the queried blog.
 760	 * 'global' - returns the global tables for the installation, returning multisite tables only if running multisite.
 761	 * 'ms_global' - returns the multisite global tables, regardless if current installation is multisite.
 762	 * 'old' - returns tables which are deprecated.
 763	 *
 764	 * @since 3.0.0
 765	 * @uses wpdb::$tables
 766	 * @uses wpdb::$old_tables
 767	 * @uses wpdb::$global_tables
 768	 * @uses wpdb::$ms_global_tables
 769	 * @uses is_multisite()
 770	 *
 771	 * @param string $scope Optional. Can be all, global, ms_global, blog, or old tables. Defaults to all.
 772	 * @param bool $prefix Optional. Whether to include table prefixes. Default true. If blog
 773	 * 	prefix is requested, then the custom users and usermeta tables will be mapped.
 774	 * @param int $blog_id Optional. The blog_id to prefix. Defaults to wpdb::$blogid. Used only when prefix is requested.
 775	 * @return array Table names. When a prefix is requested, the key is the unprefixed table name.
 776	 */
 777	function tables( $scope = 'all', $prefix = true, $blog_id = 0 ) {
 778		switch ( $scope ) {
 779			case 'all' :
 780				$tables = array_merge( $this->global_tables, $this->tables );
 781				if ( is_multisite() )
 782					$tables = array_merge( $tables, $this->ms_global_tables );
 783				break;
 784			case 'blog' :
 785				$tables = $this->tables;
 786				break;
 787			case 'global' :
 788				$tables = $this->global_tables;
 789				if ( is_multisite() )
 790					$tables = array_merge( $tables, $this->ms_global_tables );
 791				break;
 792			case 'ms_global' :
 793				$tables = $this->ms_global_tables;
 794				break;
 795			case 'old' :
 796				$tables = $this->old_tables;
 797				break;
 798			default :
 799				return array();
 800				break;
 801		}
 802
 803		if ( $prefix ) {
 804			if ( ! $blog_id )
 805				$blog_id = $this->blogid;
 806			$blog_prefix = $this->get_blog_prefix( $blog_id );
 807			$base_prefix = $this->base_prefix;
 808			$global_tables = array_merge( $this->global_tables, $this->ms_global_tables );
 809			foreach ( $tables as $k => $table ) {
 810				if ( in_array( $table, $global_tables ) )
 811					$tables[ $table ] = $base_prefix . $table;
 812				else
 813					$tables[ $table ] = $blog_prefix . $table;
 814				unset( $tables[ $k ] );
 815			}
 816
 817			if ( isset( $tables['users'] ) && defined( 'CUSTOM_USER_TABLE' ) )
 818				$tables['users'] = CUSTOM_USER_TABLE;
 819
 820			if ( isset( $tables['usermeta'] ) && defined( 'CUSTOM_USER_META_TABLE' ) )
 821				$tables['usermeta'] = CUSTOM_USER_META_TABLE;
 822		}
 823
 824		return $tables;
 825	}
 826
 827	/**
 828	 * Selects a database using the current database connection.
 829	 *
 830	 * The database name will be changed based on the current database
 831	 * connection. On failure, the execution will bail and display an DB error.
 832	 *
 833	 * @since 0.71
 834	 *
 835	 * @param string $db MySQL database name
 836	 * @param resource $dbh Optional link identifier.
 837	 * @return null Always null.
 838	 */
 839	function select( $db, $dbh = null ) {
 840		if ( is_null($dbh) )
 841			$dbh = $this->dbh;
 842
 843		if ( !@mysql_select_db( $db, $dbh ) ) {
 844			$this->ready = false;
 845			wp_load_translations_early();
 846			$this->bail( sprintf( __( '<h1>Can&#8217;t select database</h1>
 847<p>We were able to connect to the database server (which means your username and password is okay) but not able to select the <code>%1$s</code> database.</p>
 848<ul>
 849<li>Are you sure it exists?</li>
 850<li>Does the user <code>%2$s</code> have permission to use the <code>%1$s</code> database?</li>
 851<li>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?</li>
 852</ul>
 853<p>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="http://wordpress.org/support/">WordPress Support Forums</a>.</p>' ), htmlspecialchars( $db, ENT_QUOTES ), htmlspecialchars( $this->dbuser, ENT_QUOTES ) ), 'db_select_fail' );
 854			return;
 855		}
 856	}
 857
 858	/**
 859	 * Weak escape, using addslashes()
 860	 *
 861	 * @see addslashes()
 862	 * @since 2.8.0
 863	 * @access private
 864	 *
 865	 * @param string $string
 866	 * @return string
 867	 */
 868	function _weak_escape( $string ) {
 869		return addslashes( $string );
 870	}
 871
 872	/**
 873	 * Real escape, using mysql_real_escape_string() or addslashes()
 874	 *
 875	 * @see mysql_real_escape_string()
 876	 * @see addslashes()
 877	 * @since 2.8.0
 878	 * @access private
 879	 *
 880	 * @param  string $string to escape
 881	 * @return string escaped
 882	 */
 883	function _real_escape( $string ) {
 884		if ( $this->dbh && $this->real_escape )
 885			return mysql_real_escape_string( $string, $this->dbh );
 886		else
 887			return addslashes( $string );
 888	}
 889
 890	/**
 891	 * Escape data. Works on arrays.
 892	 *
 893	 * @uses wpdb::_escape()
 894	 * @uses wpdb::_real_escape()
 895	 * @since  2.8.0
 896	 * @access private
 897	 *
 898	 * @param  string|array $data
 899	 * @return string|array escaped
 900	 */
 901	function _escape( $data ) {
 902		if ( is_array( $data ) ) {
 903			foreach ( (array) $data as $k => $v ) {
 904				if ( is_array($v) )
 905					$data[$k] = $this->_escape( $v );
 906				else
 907					$data[$k] = $this->_real_escape( $v );
 908			}
 909		} else {
 910			$data = $this->_real_escape( $data );
 911		}
 912
 913		return $data;
 914	}
 915
 916	/**
 917	 * Escapes content for insertion into the database using addslashes(), for security.
 918	 *
 919	 * Works on arrays.
 920	 *
 921	 * @since 0.71
 922	 * @param string|array $data to escape
 923	 * @return string|array escaped as query safe string
 924	 */
 925	function escape( $data ) {
 926		if ( is_array( $data ) ) {
 927			foreach ( (array) $data as $k => $v ) {
 928				if ( is_array( $v ) )
 929					$data[$k] = $this->escape( $v );
 930				else
 931					$data[$k] = $this->_weak_escape( $v );
 932			}
 933		} else {
 934			$data = $this->_weak_escape( $data );
 935		}
 936
 937		return $data;
 938	}
 939
 940	/**
 941	 * Escapes content by reference for insertion into the database, for security
 942	 *
 943	 * @uses wpdb::_real_escape()
 944	 * @since 2.3.0
 945	 * @param string $string to escape
 946	 * @return void
 947	 */
 948	function escape_by_ref( &$string ) {
 949		if ( ! is_float( $string ) )
 950			$string = $this->_real_escape( $string );
 951	}
 952
 953	/**
 954	 * Prepares a SQL query for safe execution. Uses sprintf()-like syntax.
 955	 *
 956	 * The following directives can be used in the query format string:
 957	 *   %d (integer)
 958	 *   %f (float)
 959	 *   %s (string)
 960	 *   %% (literal percentage sign - no argument needed)
 961	 *
 962	 * All of %d, %f, and %s are to be left unquoted in the query string and they need an argument passed for them.
 963	 * Literals (%) as parts of the query must be properly written as %%.
 964	 *
 965	 * This function only supports a small subset of the sprintf syntax; it only supports %d (integer), %f (float), and %s (string).
 966	 * Does not support sign, padding, alignment, width or precision specifiers.
 967	 * Does not support argument numbering/swapping.
 968	 *
 969	 * May be called like {@link http://php.net/sprintf sprintf()} or like {@link http://php.net/vsprintf vsprintf()}.
 970	 *
 971	 * Both %d and %s should be left unquoted in the query string.
 972	 *
 973	 * <code>
 974	 * wpdb::prepare( "SELECT * FROM `table` WHERE `column` = %s AND `field` = %d", 'foo', 1337 )
 975	 * wpdb::prepare( "SELECT DATE_FORMAT(`field`, '%%c') FROM `table` WHERE `column` = %s", 'foo' );
 976	 * </code>
 977	 *
 978	 * @link http://php.net/sprintf Description of syntax.
 979	 * @since 2.3.0
 980	 *
 981	 * @param string $query Query statement with sprintf()-like placeholders
 982	 * @param array|mixed $args The array of variables to substitute into the query's placeholders if being called like
 983	 * 	{@link http://php.net/vsprintf vsprintf()}, or the first variable to substitute into the query's placeholders if
 984	 * 	being called like {@link http://php.net/sprintf sprintf()}.
 985	 * @param mixed $args,... further variables to substitute into the query's placeholders if being called like
 986	 * 	{@link http://php.net/sprintf sprintf()}.
 987	 * @return null|false|string Sanitized query string, null if there is no query, false if there is an error and string
 988	 * 	if there was something to prepare
 989	 */
 990	function prepare( $query, $args ) {
 991		if ( is_null( $query ) )
 992			return;
 993
 994		$args = func_get_args();
 995		array_shift( $args );
 996		// If args were passed as an array (as in vsprintf), move them up
 997		if ( isset( $args[0] ) && is_array($args[0]) )
 998			$args = $args[0];
 999		$query = str_replace( "'%s'", '%s', $query ); // in case someone mistakenly already singlequoted it
1000		$query = str_replace( '"%s"', '%s', $query ); // doublequote unquoting
1001		$query = preg_replace( '|(?<!%)%f|' , '%F', $query ); // Force floats to be locale unaware
1002		$query = preg_replace( '|(?<!%)%s|', "'%s'", $query ); // quote the strings, avoiding escaped strings like %%s
1003		array_walk( $args, array( $this, 'escape_by_ref' ) );
1004		return @vsprintf( $query, $args );
1005	}
1006
1007	/**
1008	 * Print SQL/DB error.
1009	 *
1010	 * @since 0.71
1011	 * @global array $EZSQL_ERROR Stores error information of query and error string
1012	 *
1013	 * @param string $str The error to display
1014	 * @return bool False if the showing of errors is disabled.
1015	 */
1016	function print_error( $str = '' ) {
1017		global $EZSQL_ERROR;
1018
1019		if ( !$str )
1020			$str = mysql_error( $this->dbh );
1021		$EZSQL_ERROR[] = array( 'query' => $this->last_query, 'error_str' => $str );
1022
1023		if ( $this->suppress_errors )
1024			return false;
1025
1026		wp_load_translations_early();
1027
1028		if ( $caller = $this->get_caller() )
1029			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s made by %3$s' ), $str, $this->last_query, $caller );
1030		else
1031			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s' ), $str, $this->last_query );
1032
1033		error_log( $error_str );
1034
1035		// Are we showing errors?
1036		if ( ! $this->show_errors )
1037			return false;
1038
1039		// If there is an error then take note of it
1040		if ( is_multisite() ) {
1041			$msg = "WordPress database error: [$str]\n{$this->last_query}\n";
1042			if ( defined( 'ERRORLOGFILE' ) )
1043				error_log( $msg, 3, ERRORLOGFILE );
1044			if ( defined( 'DIEONDBERROR' ) )
1045				wp_die( $msg );
1046		} else {
1047			$str   = htmlspecialchars( $str, ENT_QUOTES );
1048			$query = htmlspecialchars( $this->last_query, ENT_QUOTES );
1049
1050			print "<div id='error'>
1051			<p class='wpdberror'><strong>WordPress database error:</strong> [$str]<br />
1052			<code>$query</code></p>
1053			</div>";
1054		}
1055	}
1056
1057	/**
1058	 * Enables showing of database errors.
1059	 *
1060	 * This function should be used only to enable showing of errors.
1061	 * wpdb::hide_errors() should be used instead for hiding of errors. However,
1062	 * this function can be used to enable and disable showing of database
1063	 * errors.
1064	 *
1065	 * @since 0.71
1066	 * @see wpdb::hide_errors()
1067	 *
1068	 * @param bool $show Whether to show or hide errors
1069	 * @return bool Old value for showing errors.
1070	 */
1071	function show_errors( $show = true ) {
1072		$errors = $this->show_errors;
1073		$this->show_errors = $show;
1074		return $errors;
1075	}
1076
1077	/**
1078	 * Disables showing of database errors.
1079	 *
1080	 * By default database errors are not shown.
1081	 *
1082	 * @since 0.71
1083	 * @see wpdb::show_errors()
1084	 *
1085	 * @return bool Whether showing of errors was active
1086	 */
1087	function hide_errors() {
1088		$show = $this->show_errors;
1089		$this->show_errors = false;
1090		return $show;
1091	}
1092
1093	/**
1094	 * Whether to suppress database errors.
1095	 *
1096	 * By default database errors are suppressed, with a simple
1097	 * call to this function they can be enabled.
1098	 *
1099	 * @since 2.5.0
1100	 * @see wpdb::hide_errors()
1101	 * @param bool $suppress Optional. New value. Defaults to true.
1102	 * @return bool Old value
1103	 */
1104	function suppress_errors( $suppress = true ) {
1105		$errors = $this->suppress_errors;
1106		$this->suppress_errors = (bool) $suppress;
1107		return $errors;
1108	}
1109
1110	/**
1111	 * Kill cached query results.
1112	 *
1113	 * @since 0.71
1114	 * @return void
1115	 */
1116	function flush() {
1117		$this->last_result = array();
1118		$this->col_info    = null;
1119		$this->last_query  = null;
1120
1121		if ( is_resource( $this->result ) )
1122			mysql_free_result( $this->result );
1123	}
1124
1125	/**
1126	 * Connect to and select database
1127	 *
1128	 * @since 3.0.0
1129	 */
1130	function db_connect() {
1131
1132		$this->is_mysql = true;
1133
1134		$new_link = defined( 'MYSQL_NEW_LINK' ) ? MYSQL_NEW_LINK : true;
1135		$client_flags = defined( 'MYSQL_CLIENT_FLAGS' ) ? MYSQL_CLIENT_FLAGS : 0;
1136
1137		if ( WP_DEBUG ) {
1138			$this->dbh = mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, $new_link, $client_flags );
1139		} else {
1140			$this->dbh = @mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, $new_link, $client_flags );
1141		}
1142
1143		if ( !$this->dbh ) {
1144			wp_load_translations_early();
1145			$this->bail( sprintf( __( "
1146<h1>Error establishing a database connection</h1>
1147<p>This either means that the username and password information in your <code>wp-config.php</code> file is incorrect or we can't contact the database server at <code>%s</code>. This could mean your host's database server is down.</p>
1148<ul>
1149	<li>Are you sure you have the correct username and password?</li>
1150	<li>Are you sure that you have typed the correct hostname?</li>
1151	<li>Are you sure that the database server is running?</li>
1152</ul>
1153<p>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='http://wordpress.org/support/'>WordPress Support Forums</a>.</p>
1154" ), htmlspecialchars( $this->dbhost, ENT_QUOTES ) ), 'db_connect_fail' );
1155
1156			return;
1157		}
1158
1159		$this->set_charset( $this->dbh );
1160
1161		$this->ready = true;
1162
1163		$this->select( $this->dbname, $this->dbh );
1164	}
1165
1166	/**
1167	 * Perform a MySQL database query, using current database connection.
1168	 *
1169	 * More information can be found on the codex page.
1170	 *
1171	 * @since 0.71
1172	 *
1173	 * @param string $query Database query
1174	 * @return int|false Number of rows affected/selected or false on error
1175	 */
1176	function query( $query ) {
1177		if ( ! $this->ready )
1178			return false;
1179
1180		// some queries are made before the plugins have been loaded, and thus cannot be filtered with this method
1181		$query = apply_filters( 'query', $query );
1182
1183		$return_val = 0;
1184		$this->flush();
1185
1186		// Log how the function was called
1187		$this->func_call = "\$db->query(\"$query\")";
1188
1189		// Keep track of the last query for debug..
1190		$this->last_query = $query;
1191
1192		if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
1193			$this->timer_start();
1194
1195		$this->result = @mysql_query( $query, $this->dbh );
1196		$this->num_queries++;
1197
1198		if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
1199			$this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
1200
1201		// If there is an error then take note of it..
1202		if ( $this->last_error = mysql_error( $this->dbh ) ) {
1203			$this->print_error();
1204			return false;
1205		}
1206
1207		if ( preg_match( '/^\s*(create|alter|truncate|drop)\s/i', $query ) ) {
1208			$return_val = $this->result;
1209		} elseif ( preg_match( '/^\s*(insert|delete|update|replace)\s/i', $query ) ) {
1210			$this->rows_affected = mysql_affected_rows( $this->dbh );
1211			// Take note of the insert_id
1212			if ( preg_match( '/^\s*(insert|replace)\s/i', $query ) ) {
1213				$this->insert_id = mysql_insert_id($this->dbh);
1214			}
1215			// Return number of rows affected
1216			$return_val = $this->rows_affected;
1217		} else {
1218			$num_rows = 0;
1219			while ( $row = @mysql_fetch_object( $this->result ) ) {
1220				$this->last_result[$num_rows] = $row;
1221				$num_rows++;
1222			}
1223
1224			// Log number of rows the query returned
1225			// and return number of rows selected
1226			$this->num_rows = $num_rows;
1227			$return_val     = $num_rows;
1228		}
1229
1230		return $return_val;
1231	}
1232
1233	/**
1234	 * Insert a row into a table.
1235	 *
1236	 * <code>
1237	 * wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
1238	 * wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
1239	 * </code>
1240	 *
1241	 * @since 2.5.0
1242	 * @see wpdb::prepare()
1243	 * @see wpdb::$field_types
1244	 * @see wp_set_wpdb_vars()
1245	 *
1246	 * @param string $table table name
1247	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1248	 * @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.
1249	 * 	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.
1250	 * @return int|false The number of rows inserted, or false on error.
1251	 */
1252	function insert( $table, $data, $format = null ) {
1253		return $this->_insert_replace_helper( $table, $data, $format, 'INSERT' );
1254	}
1255
1256	/**
1257	 * Replace a row into a table.
1258	 *
1259	 * <code>
1260	 * wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
1261	 * wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
1262	 * </code>
1263	 *
1264	 * @since 3.0.0
1265	 * @see wpdb::prepare()
1266	 * @see wpdb::$field_types
1267	 * @see wp_set_wpdb_vars()
1268	 *
1269	 * @param string $table table name
1270	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1271	 * @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.
1272	 * 	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.
1273	 * @return int|false The number of rows affected, or false on error.
1274	 */
1275	function replace( $table, $data, $format = null ) {
1276		return $this->_insert_replace_helper( $table, $data, $format, 'REPLACE' );
1277	}
1278
1279	/**
1280	 * Helper function for insert and replace.
1281	 *
1282	 * Runs an insert or replace query based on $type argument.
1283	 *
1284	 * @access private
1285	 * @since 3.0.0
1286	 * @see wpdb::prepare()
1287	 * @see wpdb::$field_types
1288	 * @see wp_set_wpdb_vars()
1289	 *
1290	 * @param string $table table name
1291	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1292	 * @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.
1293	 * 	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.
1294	 * @param string $type Optional. What type of operation is this? INSERT or REPLACE. Defaults to INSERT.
1295	 * @return int|false The number of rows affected, or false on error.
1296	 */
1297	function _insert_replace_helper( $table, $data, $format = null, $type = 'INSERT' ) {
1298		if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) )
1299			return false;
1300		$formats = $format = (array) $format;
1301		$fields = array_keys( $data );
1302		$formatted_fields = array();
1303		foreach ( $fields as $field ) {
1304			if ( !empty( $format ) )
1305				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
1306			elseif ( isset( $this->field_types[$field] ) )
1307				$form = $this->field_types[$field];
1308			else
1309				$form = '%s';
1310			$formatted_fields[] = $form;
1311		}
1312		$sql = "{$type} INTO `$table` (`" . implode( '`,`', $fields ) . "`) VALUES (" . implode( ",", $formatted_fields ) . ")";
1313		return $this->query( $this->prepare( $sql, $data ) );
1314	}
1315
1316	/**
1317	 * Update a row in the table
1318	 *
1319	 * <code>
1320	 * wpdb::update( 'table', array( 'column' => 'foo', 'field' => 'bar' ), array( 'ID' => 1 ) )
1321	 * wpdb::update( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( 'ID' => 1 ), array( '%s', '%d' ), array( '%d' ) )
1322	 * </code>
1323	 *
1324	 * @since 2.5.0
1325	 * @see wpdb::prepare()
1326	 * @see wpdb::$field_types
1327	 * @see wp_set_wpdb_vars()
1328	 *
1329	 * @param string $table table name
1330	 * @param array $data Data to update (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1331	 * @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".
1332	 * @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.
1333	 * 	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.
1334	 * @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.
1335	 * @return int|false The number of rows updated, or false on error.
1336	 */
1337	function update( $table, $data, $where, $format = null, $where_format = null ) {
1338		if ( ! is_array( $data ) || ! is_array( $where ) )
1339			return false;
1340
1341		$formats = $format = (array) $format;
1342		$bits = $wheres = array();
1343		foreach ( (array) array_keys( $data ) as $field ) {
1344			if ( !empty( $format ) )
1345				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
1346			elseif ( isset($this->field_types[$field]) )
1347				$form = $this->field_types[$field];
1348			else
1349				$form = '%s';
1350			$bits[] = "`$field` = {$form}";
1351		}
1352
1353		$where_formats = $where_format = (array) $where_format;
1354		foreach ( (array) array_keys( $where ) as $field ) {
1355			if ( !empty( $where_format ) )
1356				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
1357			elseif ( isset( $this->field_types[$field] ) )
1358				$form = $this->field_types[$field];
1359			else
1360				$form = '%s';
1361			$wheres[] = "`$field` = {$form}";
1362		}
1363
1364		$sql = "UPDATE `$table` SET " . implode( ', ', $bits ) . ' WHERE ' . implode( ' AND ', $wheres );
1365		return $this->query( $this->prepare( $sql, array_merge( array_values( $data ), array_values( $where ) ) ) );
1366	}
1367
1368	/**
1369	 * Delete a row in the table
1370	 *
1371	 * <code>
1372	 * wpdb::delete( 'table', array( 'ID' => 1 ) )
1373	 * wpdb::delete( 'table', array( 'ID' => 1 ), array( '%d' ) )
1374	 * </code>
1375	 *
1376	 * @since 3.4.0
1377	 * @see wpdb::prepare()
1378	 * @see wpdb::$field_types
1379	 * @see wp_set_wpdb_vars()
1380	 *
1381	 * @param string $table table name
1382	 * @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".
1383	 * @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.
1384	 * @return int|false The number of rows updated, or false on error.
1385	 */
1386	function delete( $table, $where, $where_format = null ) {
1387		if ( ! is_array( $where ) )
1388			return false;
1389
1390		$bits = $wheres = array();
1391
1392		$where_formats = $where_format = (array) $where_format;
1393
1394		foreach ( array_keys( $where ) as $field ) {
1395			if ( !empty( $where_format ) ) {
1396				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
1397			} elseif ( isset( $this->field_types[ $field ] ) ) {
1398				$form = $this->field_types[ $field ];
1399			} else {
1400				$form = '%s';
1401			}
1402
1403			$wheres[] = "$field = $form";
1404		}
1405
1406		$sql = "DELETE FROM $table WHERE " . implode( ' AND ', $wheres );
1407		return $this->query( $this->prepare( $sql, $where ) );
1408	}
1409
1410
1411	/**
1412	 * Retrieve one variable from the database.
1413	 *
1414	 * Executes a SQL query and returns the value from the SQL result.
1415	 * 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.
1416	 * If $query is null, this function returns the value in the specified column and row from the previous SQL result.
1417	 *
1418	 * @since 0.71
1419	 *
1420	 * @param string|null $query Optional. SQL query. Defaults to null, use the result from the previous query.
1421	 * @param int $x Optional. Column of value to return. Indexed from 0.
1422	 * @param int $y Optional. Row of value to return. Indexed from 0.
1423	 * @return string|null Database query result (as string), or null on failure
1424	 */
1425	function get_var( $query = null, $x = 0, $y = 0 ) {
1426		$this->func_call = "\$db->get_var(\"$query\", $x, $y)";
1427		if ( $query )
1428			$this->query( $query );
1429
1430		// Extract var out of cached results based x,y vals
1431		if ( !empty( $this->last_result[$y] ) ) {
1432			$values = array_values( get_object_vars( $this->last_result[$y] ) );
1433		}
1434
1435		// If there is a value return it else return null
1436		return ( isset( $values[$x] ) && $values[$x] !== '' ) ? $values[$x] : null;
1437	}
1438
1439	/**
1440	 * Retrieve one row from the database.
1441	 *
1442	 * Executes a SQL query and returns the row from the SQL result.
1443	 *
1444	 * @since 0.71
1445	 *
1446	 * @param string|null $query SQL query.
1447	 * @param string $output Optional. one of ARRAY_A | ARRAY_N | OBJECT constants. Return an associative array (column => value, ...),
1448	 * 	a numerically indexed array (0 => value, ...) or an object ( ->column = value ), respectively.
1449	 * @param int $y Optional. Row to return. Indexed from 0.
1450	 * @return mixed Database query result in format specified by $output or null on failure
1451	 */
1452	function get_row( $query = null, $output = OBJECT, $y = 0 ) {
1453		$this->func_call = "\$db->get_row(\"$query\",$output,$y)";
1454		if ( $query )
1455			$this->query( $query );
1456		else
1457			return null;
1458
1459		if ( !isset( $this->last_result[$y] ) )
1460			return null;
1461
1462		if ( $output == OBJECT ) {
1463			return $this->last_result[$y] ? $this->last_result[$y] : null;
1464		} elseif ( $output == ARRAY_A ) {
1465			return $this->last_result[$y] ? get_object_vars( $this->last_result[$y] ) : null;
1466		} elseif ( $output == ARRAY_N ) {
1467			return $this->last_result[$y] ? array_values( get_object_vars( $this->last_result[$y] ) ) : null;
1468		} else {
1469			$this->print_error( " \$db->get_row(string query, output type, int offset) -- Output type must be one of: OBJECT, ARRAY_A, ARRAY_N" );
1470		}
1471	}
1472
1473	/**
1474	 * Retrieve one column from the database.
1475	 *
1476	 * Executes a SQL query and returns the column from the SQL result.
1477	 * If the SQL result contains more than one column, this function returns the column specified.
1478	 * If $query is null, this function returns the specified column from the previous SQL result.
1479	 *
1480	 * @since 0.71
1481	 *
1482	 * @param string|null $query Optional. SQL query. Defaults to previous query.
1483	 * @param int $x Optional. Column to return. Indexed from 0.
1484	 * @return array Database query result. Array indexed from 0 by SQL result row number.
1485	 */
1486	function get_col( $query = null , $x = 0 ) {
1487		if ( $query )
1488			$this->query( $query );
1489
1490		$new_array = array();
1491		// Extract the column values
1492		for ( $i = 0, $j = count( $this->last_result ); $i < $j; $i++ ) {
1493			$new_array[$i] = $this->get_var( null, $x, $i );
1494		}
1495		return $new_array;
1496	}
1497
1498	/**
1499	 * Retrieve an entire SQL result set from the database (i.e., many rows)
1500	 *
1501	 * Executes a SQL query and returns the entire SQL result.
1502	 *
1503	 * @since 0.71
1504	 *
1505	 * @param string $query SQL query.
1506	 * @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.
1507	 * 	Each row is an associative array (column => value, ...), a numerically indexed array (0 => value, ...), or an object. ( ->column = value ), respectively.
1508	 * 	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.
1509	 * @return mixed Database query results
1510	 */
1511	function get_results( $query = null, $output = OBJECT ) {
1512		$this->func_call = "\$db->get_results(\"$query\", $output)";
1513
1514		if ( $query )
1515			$this->query( $query );
1516		else
1517			return null;
1518
1519		$new_array = array();
1520		if ( $output == OBJECT ) {
1521			// Return an integer-keyed array of row objects
1522			return $this->last_result;
1523		} elseif ( $output == OBJECT_K ) {
1524			// Return an array of row objects with keys from column 1
1525			// (Duplicates are discarded)
1526			foreach ( $this->last_result as $row ) {
1527				$var_by_ref = get_object_vars( $row );
1528				$key = array_shift( $var_by_ref );
1529				if ( ! isset( $new_array[ $key ] ) )
1530					$new_array[ $key ] = $row;
1531			}
1532			return $new_array;
1533		} elseif ( $output == ARRAY_A || $output == ARRAY_N ) {
1534			// Return an integer-keyed array of...
1535			if ( $this->last_result ) {
1536				foreach( (array) $this->last_result as $row ) {
1537					if ( $output == ARRAY_N ) {
1538						// ...integer-keyed row arrays
1539						$new_array[] = array_values( get_object_vars( $row ) );
1540					} else {
1541						// ...column name-keyed row arrays
1542						$new_array[] = get_object_vars( $row );
1543					}
1544				}
1545			}
1546			return $new_array;
1547		}
1548		return null;
1549	}
1550
1551	/**
1552	 * Load the column metadata from the last query.
1553	 *
1554	 * @since 3.5.0
1555	 *
1556	 * @access protected
1557	 */
1558	protected function load_col_info() {
1559		if ( $this->col_info )
1560			return;
1561
1562		for ( $i = 0; $i < @mysql_num_fields( $this->result ); $i++ ) {
1563			$this->col_info[ $i ] = @mysql_fetch_field( $this->result, $i );
1564		}
1565	}
1566
1567	/**
1568	 * Retrieve column metadata from the last query.
1569	 *
1570	 * @since 0.71
1571	 *
1572	 * @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
1573	 * @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
1574	 * @return mixed Column Results
1575	 */
1576	function get_col_info( $info_type = 'name', $col_offset = -1 ) {
1577		$this->load_col_info();
1578
1579		if ( $this->col_info ) {
1580			if ( $col_offset == -1 ) {
1581				$i = 0;
1582				$new_array = array();
1583				foreach( (array) $this->col_info as $col ) {
1584					$new_array[$i] = $col->{$info_type};
1585					$i++;
1586				}
1587				return $new_array;
1588			} else {
1589				return $this->col_info[$col_offset]->{$info_type};
1590			}
1591		}
1592	}
1593
1594	/**
1595	 * Starts the timer, for debugging purposes.
1596	 *
1597	 * @since 1.5.0
1598	 *
1599	 * @return true
1600	 */
1601	function timer_start() {
1602		$this->time_start = microtime( true );
1603		return true;
1604	}
1605
1606	/**
1607	 * Stops the debugging timer.
1608	 *
1609	 * @since 1.5.0
1610	 *
1611	 * @return float Total time spent on the query, in seconds
1612	 */
1613	function timer_stop() {
1614		return ( microtime( true ) - $this->time_start );
1615	}
1616
1617	/**
1618	 * Wraps errors in a nice header and footer and dies.
1619	 *
1620	 * Will not die if wpdb::$show_errors is false.
1621	 *
1622	 * @since 1.5.0
1623	 *
1624	 * @param string $message The Error message
1625	 * @param string $error_code Optional. A Computer readable string to identify the error.
1626	 * @return false|void
1627	 */
1628	function bail( $message, $error_code = '500' ) {
1629		if ( !$this->show_errors ) {
1630			if ( class_exists( 'WP_Error' ) )
1631				$this->error = new WP_Error($error_code, $message);
1632			else
1633				$this->error = $message;
1634			return false;
1635		}
1636		wp_die($message);
1637	}
1638
1639	/**
1640	 * Whether MySQL database is at least the required minimum version.
1641	 *
1642	 * @since 2.5.0
1643	 * @uses $wp_version
1644	 * @uses $required_mysql_version
1645	 *
1646	 * @return WP_Error
1647	 */
1648	function check_database_version() {
1649		global $wp_version, $required_mysql_version;
1650		// Make sure the server has the required MySQL version
1651		if ( version_compare($this->db_version(), $required_mysql_version, '<') )
1652			return new WP_Error('database_version', sprintf( __( '<strong>ERROR</strong>: WordPress %1$s requires MySQL %2$s or higher' ), $wp_version, $required_mysql_version ));
1653	}
1654
1655	/**
1656	 * Whether the database supports collation.
1657	 *
1658	 * Called when WordPress is generating the table scheme.
1659	 *
1660	 * @since 2.5.0
1661	 * @deprecated 3.5.0
1662	 * @deprecated Use wpdb::has_cap( 'collation' )
1663	 *
1664	 * @return bool True if collation is supported, false if version does not
1665	 */
1666	function supports_collation() {
1667		_deprecated_function( __FUNCTION__, '3.5', 'wpdb::has_cap( \'collation\' )' );
1668		return $this->has_cap( 'collation' );
1669	}
1670
1671	/**
1672	 * The database character collate.
1673	 *
1674	 * @since 3.5.0
1675	 *
1676	 * @return string The database character collate.
1677	 */
1678	public function get_charset_collate() {
1679		$charset_collate = '';
1680
1681		if ( ! empty( $this->charset ) )
1682			$charset_collate = "DEFAULT CHARACTER SET $this->charset";
1683		if ( ! empty( $this->collate ) )
1684			$charset_collate .= " COLLATE $this->collate";
1685
1686		return $charset_collate;
1687	}
1688
1689	/**
1690	 * Determine if a database supports a particular feature
1691	 *
1692	 * @since 2.7.0
1693	 * @see   wpdb::db_version()
1694	 *
1695	 * @param string $db_cap the feature
1696	 * @return bool
1697	 */
1698	function has_cap( $db_cap ) {
1699		$version = $this->db_version();
1700
1701		switch ( strtolower( $db_cap ) ) {
1702			case 'collation' :    // @since 2.5.0
1703			case 'group_concat' : // @since 2.7
1704			case 'subqueries' :   // @since 2.7
1705				return version_compare( $version, '4.1', '>=' );
1706			case 'set_charset' :
1707				return version_compare($version, '5.0.7', '>=');
1708		};
1709
1710		return false;
1711	}
1712
1713	/**
1714	 * Retrieve the name of the function that called wpdb.
1715	 *
1716	 * Searches up the list of functions until it reaches
1717	 * the one that would most logically had called this method.
1718	 *
1719	 * @since 2.5.0
1720	 *
1721	 * @return string The name of the calling function
1722	 */
1723	function get_caller() {
1724		return wp_debug_backtrace_summary( __CLASS__ );
1725	}
1726
1727	/**
1728	 * The database version number.
1729	 *
1730	 * @since 2.7.0
1731	 *
1732	 * @return false|string false on failure, version number on success
1733	 */
1734	function db_version() {
1735		return preg_replace( '/[^0-9.].*/', '', mysql_get_server_info( $this->dbh ) );
1736	}
1737}