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/Web/wp-includes/wp-db.php

https://bitbucket.org/jimjenkins5/blog
PHP | 1605 lines | 572 code | 163 blank | 870 comment | 119 complexity | 8b9983438550184586b2923f34671e2f MD5 | raw file
Possible License(s): GPL-2.0, GPL-3.0, AGPL-1.0, LGPL-2.1
   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 1.2.0
  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	 * Saved result of the last query made
 117	 *
 118	 * @since 1.2.0
 119	 * @access private
 120	 * @var array
 121	 */
 122	var $last_query;
 123
 124	/**
 125	 * Results of the last query made
 126	 *
 127	 * @since 1.0.0
 128	 * @access private
 129	 * @var array|null
 130	 */
 131	var $last_result;
 132
 133	/**
 134	 * Saved info on the table column
 135	 *
 136	 * @since 1.2.0
 137	 * @access private
 138	 * @var array
 139	 */
 140	var $col_info;
 141
 142	/**
 143	 * Saved queries that were executed
 144	 *
 145	 * @since 1.5.0
 146	 * @access private
 147	 * @var array
 148	 */
 149	var $queries;
 150
 151	/**
 152	 * WordPress table prefix
 153	 *
 154	 * You can set this to have multiple WordPress installations
 155	 * in a single database. The second reason is for possible
 156	 * security precautions.
 157	 *
 158	 * @since 0.71
 159	 * @access private
 160	 * @var string
 161	 */
 162	var $prefix = '';
 163
 164	/**
 165	 * Whether the database queries are ready to start executing.
 166	 *
 167	 * @since 2.5.0
 168	 * @access private
 169	 * @var bool
 170	 */
 171	var $ready = false;
 172
 173	/**
 174	 * {@internal Missing Description}}
 175	 *
 176	 * @since 3.0.0
 177	 * @access public
 178	 * @var int
 179	 */
 180	var $blogid = 0;
 181
 182	/**
 183	 * {@internal Missing Description}}
 184	 *
 185	 * @since 3.0.0
 186	 * @access public
 187	 * @var int
 188	 */
 189	var $siteid = 0;
 190
 191	/**
 192	 * List of WordPress per-blog tables
 193	 *
 194	 * @since 2.5.0
 195	 * @access private
 196	 * @see wpdb::tables()
 197	 * @var array
 198	 */
 199	var $tables = array( 'posts', 'comments', 'links', 'options', 'postmeta',
 200		'terms', 'term_taxonomy', 'term_relationships', 'commentmeta' );
 201
 202	/**
 203	 * List of deprecated WordPress tables
 204	 *
 205	 * categories, post2cat, and link2cat were deprecated in 2.3.0, db version 5539
 206	 *
 207	 * @since 2.9.0
 208	 * @access private
 209	 * @see wpdb::tables()
 210	 * @var array
 211	 */
 212	var $old_tables = array( 'categories', 'post2cat', 'link2cat' );
 213
 214	/**
 215	 * List of WordPress global tables
 216	 *
 217	 * @since 3.0.0
 218	 * @access private
 219	 * @see wpdb::tables()
 220	 * @var array
 221	 */
 222	var $global_tables = array( 'users', 'usermeta' );
 223
 224	/**
 225	 * List of Multisite global tables
 226	 *
 227	 * @since 3.0.0
 228	 * @access private
 229	 * @see wpdb::tables()
 230	 * @var array
 231	 */
 232	var $ms_global_tables = array( 'blogs', 'signups', 'site', 'sitemeta',
 233		'sitecategories', 'registration_log', 'blog_versions' );
 234
 235	/**
 236	 * WordPress Comments table
 237	 *
 238	 * @since 1.5.0
 239	 * @access public
 240	 * @var string
 241	 */
 242	var $comments;
 243
 244	/**
 245	 * WordPress Comment Metadata table
 246	 *
 247	 * @since 2.9.0
 248	 * @access public
 249	 * @var string
 250	 */
 251	var $commentmeta;
 252
 253	/**
 254	 * WordPress Links table
 255	 *
 256	 * @since 1.5.0
 257	 * @access public
 258	 * @var string
 259	 */
 260	var $links;
 261
 262	/**
 263	 * WordPress Options table
 264	 *
 265	 * @since 1.5.0
 266	 * @access public
 267	 * @var string
 268	 */
 269	var $options;
 270
 271	/**
 272	 * WordPress Post Metadata table
 273	 *
 274	 * @since 1.5.0
 275	 * @access public
 276	 * @var string
 277	 */
 278	var $postmeta;
 279
 280	/**
 281	 * WordPress Posts table
 282	 *
 283	 * @since 1.5.0
 284	 * @access public
 285	 * @var string
 286	 */
 287	var $posts;
 288
 289	/**
 290	 * WordPress Terms table
 291	 *
 292	 * @since 2.3.0
 293	 * @access public
 294	 * @var string
 295	 */
 296	var $terms;
 297
 298	/**
 299	 * WordPress Term Relationships table
 300	 *
 301	 * @since 2.3.0
 302	 * @access public
 303	 * @var string
 304	 */
 305	var $term_relationships;
 306
 307	/**
 308	 * WordPress Term Taxonomy table
 309	 *
 310	 * @since 2.3.0
 311	 * @access public
 312	 * @var string
 313	 */
 314	var $term_taxonomy;
 315
 316	/*
 317	 * Global and Multisite tables
 318	 */
 319
 320	/**
 321	 * WordPress User Metadata table
 322	 *
 323	 * @since 2.3.0
 324	 * @access public
 325	 * @var string
 326	 */
 327	var $usermeta;
 328
 329	/**
 330	 * WordPress Users table
 331	 *
 332	 * @since 1.5.0
 333	 * @access public
 334	 * @var string
 335	 */
 336	var $users;
 337
 338	/**
 339	 * Multisite Blogs table
 340	 *
 341	 * @since 3.0.0
 342	 * @access public
 343	 * @var string
 344	 */
 345	var $blogs;
 346
 347	/**
 348	 * Multisite Blog Versions table
 349	 *
 350	 * @since 3.0.0
 351	 * @access public
 352	 * @var string
 353	 */
 354	var $blog_versions;
 355
 356	/**
 357	 * Multisite Registration Log table
 358	 *
 359	 * @since 3.0.0
 360	 * @access public
 361	 * @var string
 362	 */
 363	var $registration_log;
 364
 365	/**
 366	 * Multisite Signups table
 367	 *
 368	 * @since 3.0.0
 369	 * @access public
 370	 * @var string
 371	 */
 372	var $signups;
 373
 374	/**
 375	 * Multisite Sites table
 376	 *
 377	 * @since 3.0.0
 378	 * @access public
 379	 * @var string
 380	 */
 381	var $site;
 382
 383	/**
 384	 * Multisite Sitewide Terms table
 385	 *
 386	 * @since 3.0.0
 387	 * @access public
 388	 * @var string
 389	 */
 390	var $sitecategories;
 391
 392	/**
 393	 * Multisite Site Metadata table
 394	 *
 395	 * @since 3.0.0
 396	 * @access public
 397	 * @var string
 398	 */
 399	var $sitemeta;
 400
 401	/**
 402	 * Format specifiers for DB columns. Columns not listed here default to %s. Initialized during WP load.
 403	 *
 404	 * Keys are column names, values are format types: 'ID' => '%d'
 405	 *
 406	 * @since 2.8.0
 407	 * @see wpdb::prepare()
 408	 * @see wpdb::insert()
 409	 * @see wpdb::update()
 410	 * @see wpdb::delete()
 411	 * @see wp_set_wpdb_vars()
 412	 * @access public
 413	 * @var array
 414	 */
 415	var $field_types = array();
 416
 417	/**
 418	 * Database table columns charset
 419	 *
 420	 * @since 2.2.0
 421	 * @access public
 422	 * @var string
 423	 */
 424	var $charset;
 425
 426	/**
 427	 * Database table columns collate
 428	 *
 429	 * @since 2.2.0
 430	 * @access public
 431	 * @var string
 432	 */
 433	var $collate;
 434
 435	/**
 436	 * Whether to use mysql_real_escape_string
 437	 *
 438	 * @since 2.8.0
 439	 * @access public
 440	 * @var bool
 441	 */
 442	var $real_escape = false;
 443
 444	/**
 445	 * Database Username
 446	 *
 447	 * @since 2.9.0
 448	 * @access private
 449	 * @var string
 450	 */
 451	var $dbuser;
 452
 453	/**
 454	 * A textual description of the last query/get_row/get_var call
 455	 *
 456	 * @since 3.0.0
 457	 * @access public
 458	 * @var string
 459	 */
 460	var $func_call;
 461
 462	/**
 463	 * Whether MySQL is used as the database engine.
 464	 *
 465	 * Set in WPDB::db_connect() to true, by default. This is used when checking
 466	 * against the required MySQL version for WordPress. Normally, a replacement
 467	 * database drop-in (db.php) will skip these checks, but setting this to true
 468	 * will force the checks to occur.
 469	 *
 470	 * @since 3.3.0
 471	 * @access public
 472	 * @var bool
 473	 */
 474	public $is_mysql = null;
 475
 476	/**
 477	 * Connects to the database server and selects a database
 478	 *
 479	 * PHP5 style constructor for compatibility with PHP5. Does
 480	 * the actual setting up of the class properties and connection
 481	 * to the database.
 482	 *
 483	 * @link http://core.trac.wordpress.org/ticket/3354
 484	 * @since 2.0.8
 485	 *
 486	 * @param string $dbuser MySQL database user
 487	 * @param string $dbpassword MySQL database password
 488	 * @param string $dbname MySQL database name
 489	 * @param string $dbhost MySQL database host
 490	 */
 491	function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {
 492		register_shutdown_function( array( &$this, '__destruct' ) );
 493
 494		if ( WP_DEBUG )
 495			$this->show_errors();
 496
 497		$this->init_charset();
 498
 499		$this->dbuser = $dbuser;
 500		$this->dbpassword = $dbpassword;
 501		$this->dbname = $dbname;
 502		$this->dbhost = $dbhost;
 503
 504		$this->db_connect();
 505	}
 506
 507	/**
 508	 * PHP5 style destructor and will run when database object is destroyed.
 509	 *
 510	 * @see wpdb::__construct()
 511	 * @since 2.0.8
 512	 * @return bool true
 513	 */
 514	function __destruct() {
 515		return true;
 516	}
 517
 518	/**
 519	 * Set $this->charset and $this->collate
 520	 *
 521	 * @since 3.1.0
 522	 */
 523	function init_charset() {
 524		if ( function_exists('is_multisite') && is_multisite() ) {
 525			$this->charset = 'utf8';
 526			if ( defined( 'DB_COLLATE' ) && DB_COLLATE )
 527				$this->collate = DB_COLLATE;
 528			else
 529				$this->collate = 'utf8_general_ci';
 530		} elseif ( defined( 'DB_COLLATE' ) ) {
 531			$this->collate = DB_COLLATE;
 532		}
 533
 534		if ( defined( 'DB_CHARSET' ) )
 535			$this->charset = DB_CHARSET;
 536	}
 537
 538	/**
 539	 * Sets the connection's character set.
 540	 *
 541	 * @since 3.1.0
 542	 *
 543	 * @param resource $dbh     The resource given by mysql_connect
 544	 * @param string   $charset The character set (optional)
 545	 * @param string   $collate The collation (optional)
 546	 */
 547	function set_charset($dbh, $charset = null, $collate = null) {
 548		if ( !isset($charset) )
 549			$charset = $this->charset;
 550		if ( !isset($collate) )
 551			$collate = $this->collate;
 552		if ( $this->has_cap( 'collation', $dbh ) && !empty( $charset ) ) {
 553			if ( function_exists( 'mysql_set_charset' ) && $this->has_cap( 'set_charset', $dbh ) ) {
 554				mysql_set_charset( $charset, $dbh );
 555				$this->real_escape = true;
 556			} else {
 557				$query = $this->prepare( 'SET NAMES %s', $charset );
 558				if ( ! empty( $collate ) )
 559					$query .= $this->prepare( ' COLLATE %s', $collate );
 560				mysql_query( $query, $dbh );
 561			}
 562		}
 563	}
 564
 565	/**
 566	 * Sets the table prefix for the WordPress tables.
 567	 *
 568	 * @since 2.5.0
 569	 *
 570	 * @param string $prefix Alphanumeric name for the new prefix.
 571	 * @param bool $set_table_names Optional. Whether the table names, e.g. wpdb::$posts, should be updated or not.
 572	 * @return string|WP_Error Old prefix or WP_Error on error
 573	 */
 574	function set_prefix( $prefix, $set_table_names = true ) {
 575
 576		if ( preg_match( '|[^a-z0-9_]|i', $prefix ) )
 577			return new WP_Error('invalid_db_prefix', 'Invalid database prefix' );
 578
 579		$old_prefix = is_multisite() ? '' : $prefix;
 580
 581		if ( isset( $this->base_prefix ) )
 582			$old_prefix = $this->base_prefix;
 583
 584		$this->base_prefix = $prefix;
 585
 586		if ( $set_table_names ) {
 587			foreach ( $this->tables( 'global' ) as $table => $prefixed_table )
 588				$this->$table = $prefixed_table;
 589
 590			if ( is_multisite() && empty( $this->blogid ) )
 591				return $old_prefix;
 592
 593			$this->prefix = $this->get_blog_prefix();
 594
 595			foreach ( $this->tables( 'blog' ) as $table => $prefixed_table )
 596				$this->$table = $prefixed_table;
 597
 598			foreach ( $this->tables( 'old' ) as $table => $prefixed_table )
 599				$this->$table = $prefixed_table;
 600		}
 601		return $old_prefix;
 602	}
 603
 604	/**
 605	 * Sets blog id.
 606	 *
 607	 * @since 3.0.0
 608	 * @access public
 609	 * @param int $blog_id
 610	 * @param int $site_id Optional.
 611	 * @return string previous blog id
 612	 */
 613	function set_blog_id( $blog_id, $site_id = 0 ) {
 614		if ( ! empty( $site_id ) )
 615			$this->siteid = $site_id;
 616
 617		$old_blog_id  = $this->blogid;
 618		$this->blogid = $blog_id;
 619
 620		$this->prefix = $this->get_blog_prefix();
 621
 622		foreach ( $this->tables( 'blog' ) as $table => $prefixed_table )
 623			$this->$table = $prefixed_table;
 624
 625		foreach ( $this->tables( 'old' ) as $table => $prefixed_table )
 626			$this->$table = $prefixed_table;
 627
 628		return $old_blog_id;
 629	}
 630
 631	/**
 632	 * Gets blog prefix.
 633	 *
 634	 * @uses is_multisite()
 635	 * @since 3.0.0
 636	 * @param int $blog_id Optional.
 637	 * @return string Blog prefix.
 638	 */
 639	function get_blog_prefix( $blog_id = null ) {
 640		if ( is_multisite() ) {
 641			if ( null === $blog_id )
 642				$blog_id = $this->blogid;
 643			$blog_id = (int) $blog_id;
 644			if ( defined( 'MULTISITE' ) && ( 0 == $blog_id || 1 == $blog_id ) )
 645				return $this->base_prefix;
 646			else
 647				return $this->base_prefix . $blog_id . '_';
 648		} else {
 649			return $this->base_prefix;
 650		}
 651	}
 652
 653	/**
 654	 * Returns an array of WordPress tables.
 655	 *
 656	 * Also allows for the CUSTOM_USER_TABLE and CUSTOM_USER_META_TABLE to
 657	 * override the WordPress users and usermeta tables that would otherwise
 658	 * be determined by the prefix.
 659	 *
 660	 * The scope argument can take one of the following:
 661	 *
 662	 * 'all' - returns 'all' and 'global' tables. No old tables are returned.
 663	 * 'blog' - returns the blog-level tables for the queried blog.
 664	 * 'global' - returns the global tables for the installation, returning multisite tables only if running multisite.
 665	 * 'ms_global' - returns the multisite global tables, regardless if current installation is multisite.
 666	 * 'old' - returns tables which are deprecated.
 667	 *
 668	 * @since 3.0.0
 669	 * @uses wpdb::$tables
 670	 * @uses wpdb::$old_tables
 671	 * @uses wpdb::$global_tables
 672	 * @uses wpdb::$ms_global_tables
 673	 * @uses is_multisite()
 674	 *
 675	 * @param string $scope Optional. Can be all, global, ms_global, blog, or old tables. Defaults to all.
 676	 * @param bool $prefix Optional. Whether to include table prefixes. Default true. If blog
 677	 * 	prefix is requested, then the custom users and usermeta tables will be mapped.
 678	 * @param int $blog_id Optional. The blog_id to prefix. Defaults to wpdb::$blogid. Used only when prefix is requested.
 679	 * @return array Table names. When a prefix is requested, the key is the unprefixed table name.
 680	 */
 681	function tables( $scope = 'all', $prefix = true, $blog_id = 0 ) {
 682		switch ( $scope ) {
 683			case 'all' :
 684				$tables = array_merge( $this->global_tables, $this->tables );
 685				if ( is_multisite() )
 686					$tables = array_merge( $tables, $this->ms_global_tables );
 687				break;
 688			case 'blog' :
 689				$tables = $this->tables;
 690				break;
 691			case 'global' :
 692				$tables = $this->global_tables;
 693				if ( is_multisite() )
 694					$tables = array_merge( $tables, $this->ms_global_tables );
 695				break;
 696			case 'ms_global' :
 697				$tables = $this->ms_global_tables;
 698				break;
 699			case 'old' :
 700				$tables = $this->old_tables;
 701				break;
 702			default :
 703				return array();
 704				break;
 705		}
 706
 707		if ( $prefix ) {
 708			if ( ! $blog_id )
 709				$blog_id = $this->blogid;
 710			$blog_prefix = $this->get_blog_prefix( $blog_id );
 711			$base_prefix = $this->base_prefix;
 712			$global_tables = array_merge( $this->global_tables, $this->ms_global_tables );
 713			foreach ( $tables as $k => $table ) {
 714				if ( in_array( $table, $global_tables ) )
 715					$tables[ $table ] = $base_prefix . $table;
 716				else
 717					$tables[ $table ] = $blog_prefix . $table;
 718				unset( $tables[ $k ] );
 719			}
 720
 721			if ( isset( $tables['users'] ) && defined( 'CUSTOM_USER_TABLE' ) )
 722				$tables['users'] = CUSTOM_USER_TABLE;
 723
 724			if ( isset( $tables['usermeta'] ) && defined( 'CUSTOM_USER_META_TABLE' ) )
 725				$tables['usermeta'] = CUSTOM_USER_META_TABLE;
 726		}
 727
 728		return $tables;
 729	}
 730
 731	/**
 732	 * Selects a database using the current database connection.
 733	 *
 734	 * The database name will be changed based on the current database
 735	 * connection. On failure, the execution will bail and display an DB error.
 736	 *
 737	 * @since 0.71
 738	 *
 739	 * @param string $db MySQL database name
 740	 * @param resource $dbh Optional link identifier.
 741	 * @return null Always null.
 742	 */
 743	function select( $db, $dbh = null ) {
 744		if ( is_null($dbh) )
 745			$dbh = $this->dbh;
 746
 747		if ( !@mysql_select_db( $db, $dbh ) ) {
 748			$this->ready = false;
 749			wp_load_translations_early();
 750			$this->bail( sprintf( __( '<h1>Can&#8217;t select database</h1>
 751<p>We were able to connect to the database server (which means your username and password is okay) but not able to select the <code>%1$s</code> database.</p>
 752<ul>
 753<li>Are you sure it exists?</li>
 754<li>Does the user <code>%2$s</code> have permission to use the <code>%1$s</code> database?</li>
 755<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>
 756</ul>
 757<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' );
 758			return;
 759		}
 760	}
 761
 762	/**
 763	 * Weak escape, using addslashes()
 764	 *
 765	 * @see addslashes()
 766	 * @since 2.8.0
 767	 * @access private
 768	 *
 769	 * @param string $string
 770	 * @return string
 771	 */
 772	function _weak_escape( $string ) {
 773		return addslashes( $string );
 774	}
 775
 776	/**
 777	 * Real escape, using mysql_real_escape_string() or addslashes()
 778	 *
 779	 * @see mysql_real_escape_string()
 780	 * @see addslashes()
 781	 * @since 2.8.0
 782	 * @access private
 783	 *
 784	 * @param  string $string to escape
 785	 * @return string escaped
 786	 */
 787	function _real_escape( $string ) {
 788		if ( $this->dbh && $this->real_escape )
 789			return mysql_real_escape_string( $string, $this->dbh );
 790		else
 791			return addslashes( $string );
 792	}
 793
 794	/**
 795	 * Escape data. Works on arrays.
 796	 *
 797	 * @uses wpdb::_escape()
 798	 * @uses wpdb::_real_escape()
 799	 * @since  2.8.0
 800	 * @access private
 801	 *
 802	 * @param  string|array $data
 803	 * @return string|array escaped
 804	 */
 805	function _escape( $data ) {
 806		if ( is_array( $data ) ) {
 807			foreach ( (array) $data as $k => $v ) {
 808				if ( is_array($v) )
 809					$data[$k] = $this->_escape( $v );
 810				else
 811					$data[$k] = $this->_real_escape( $v );
 812			}
 813		} else {
 814			$data = $this->_real_escape( $data );
 815		}
 816
 817		return $data;
 818	}
 819
 820	/**
 821	 * Escapes content for insertion into the database using addslashes(), for security.
 822	 *
 823	 * Works on arrays.
 824	 *
 825	 * @since 0.71
 826	 * @param string|array $data to escape
 827	 * @return string|array escaped as query safe string
 828	 */
 829	function escape( $data ) {
 830		if ( is_array( $data ) ) {
 831			foreach ( (array) $data as $k => $v ) {
 832				if ( is_array( $v ) )
 833					$data[$k] = $this->escape( $v );
 834				else
 835					$data[$k] = $this->_weak_escape( $v );
 836			}
 837		} else {
 838			$data = $this->_weak_escape( $data );
 839		}
 840
 841		return $data;
 842	}
 843
 844	/**
 845	 * Escapes content by reference for insertion into the database, for security
 846	 *
 847	 * @uses wpdb::_real_escape()
 848	 * @since 2.3.0
 849	 * @param string $string to escape
 850	 * @return void
 851	 */
 852	function escape_by_ref( &$string ) {
 853		$string = $this->_real_escape( $string );
 854	}
 855
 856	/**
 857	 * Prepares a SQL query for safe execution. Uses sprintf()-like syntax.
 858	 *
 859	 * The following directives can be used in the query format string:
 860	 *   %d (integer)
 861	 *   %f (float)
 862	 *   %s (string)
 863	 *   %% (literal percentage sign - no argument needed)
 864	 *
 865	 * All of %d, %f, and %s are to be left unquoted in the query string and they need an argument passed for them.
 866	 * Literals (%) as parts of the query must be properly written as %%.
 867	 *
 868	 * This function only supports a small subset of the sprintf syntax; it only supports %d (integer), %f (float), and %s (string).
 869	 * Does not support sign, padding, alignment, width or precision specifiers.
 870	 * Does not support argument numbering/swapping.
 871	 *
 872	 * May be called like {@link http://php.net/sprintf sprintf()} or like {@link http://php.net/vsprintf vsprintf()}.
 873	 *
 874	 * Both %d and %s should be left unquoted in the query string.
 875	 *
 876	 * <code>
 877	 * wpdb::prepare( "SELECT * FROM `table` WHERE `column` = %s AND `field` = %d", 'foo', 1337 )
 878	 * wpdb::prepare( "SELECT DATE_FORMAT(`field`, '%%c') FROM `table` WHERE `column` = %s", 'foo' );
 879	 * </code>
 880	 *
 881	 * @link http://php.net/sprintf Description of syntax.
 882	 * @since 2.3.0
 883	 *
 884	 * @param string $query Query statement with sprintf()-like placeholders
 885	 * @param array|mixed $args The array of variables to substitute into the query's placeholders if being called like
 886	 * 	{@link http://php.net/vsprintf vsprintf()}, or the first variable to substitute into the query's placeholders if
 887	 * 	being called like {@link http://php.net/sprintf sprintf()}.
 888	 * @param mixed $args,... further variables to substitute into the query's placeholders if being called like
 889	 * 	{@link http://php.net/sprintf sprintf()}.
 890	 * @return null|false|string Sanitized query string, null if there is no query, false if there is an error and string
 891	 * 	if there was something to prepare
 892	 */
 893	function prepare( $query = null ) { // ( $query, *$args )
 894		if ( is_null( $query ) )
 895			return;
 896
 897		$args = func_get_args();
 898		array_shift( $args );
 899		// If args were passed as an array (as in vsprintf), move them up
 900		if ( isset( $args[0] ) && is_array($args[0]) )
 901			$args = $args[0];
 902		$query = str_replace( "'%s'", '%s', $query ); // in case someone mistakenly already singlequoted it
 903		$query = str_replace( '"%s"', '%s', $query ); // doublequote unquoting
 904		$query = preg_replace( '|(?<!%)%s|', "'%s'", $query ); // quote the strings, avoiding escaped strings like %%s
 905		array_walk( $args, array( &$this, 'escape_by_ref' ) );
 906		return @vsprintf( $query, $args );
 907	}
 908
 909	/**
 910	 * Print SQL/DB error.
 911	 *
 912	 * @since 0.71
 913	 * @global array $EZSQL_ERROR Stores error information of query and error string
 914	 *
 915	 * @param string $str The error to display
 916	 * @return bool False if the showing of errors is disabled.
 917	 */
 918	function print_error( $str = '' ) {
 919		global $EZSQL_ERROR;
 920
 921		if ( !$str )
 922			$str = mysql_error( $this->dbh );
 923		$EZSQL_ERROR[] = array( 'query' => $this->last_query, 'error_str' => $str );
 924
 925		if ( $this->suppress_errors )
 926			return false;
 927
 928		wp_load_translations_early();
 929
 930		if ( $caller = $this->get_caller() )
 931			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s made by %3$s' ), $str, $this->last_query, $caller );
 932		else
 933			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s' ), $str, $this->last_query );
 934
 935		if ( function_exists( 'error_log' )
 936			&& ( $log_file = @ini_get( 'error_log' ) )
 937			&& ( 'syslog' == $log_file || @is_writable( $log_file ) )
 938			)
 939			@error_log( $error_str );
 940
 941		// Are we showing errors?
 942		if ( ! $this->show_errors )
 943			return false;
 944
 945		// If there is an error then take note of it
 946		if ( is_multisite() ) {
 947			$msg = "WordPress database error: [$str]\n{$this->last_query}\n";
 948			if ( defined( 'ERRORLOGFILE' ) )
 949				error_log( $msg, 3, ERRORLOGFILE );
 950			if ( defined( 'DIEONDBERROR' ) )
 951				wp_die( $msg );
 952		} else {
 953			$str   = htmlspecialchars( $str, ENT_QUOTES );
 954			$query = htmlspecialchars( $this->last_query, ENT_QUOTES );
 955
 956			print "<div id='error'>
 957			<p class='wpdberror'><strong>WordPress database error:</strong> [$str]<br />
 958			<code>$query</code></p>
 959			</div>";
 960		}
 961	}
 962
 963	/**
 964	 * Enables showing of database errors.
 965	 *
 966	 * This function should be used only to enable showing of errors.
 967	 * wpdb::hide_errors() should be used instead for hiding of errors. However,
 968	 * this function can be used to enable and disable showing of database
 969	 * errors.
 970	 *
 971	 * @since 0.71
 972	 * @see wpdb::hide_errors()
 973	 *
 974	 * @param bool $show Whether to show or hide errors
 975	 * @return bool Old value for showing errors.
 976	 */
 977	function show_errors( $show = true ) {
 978		$errors = $this->show_errors;
 979		$this->show_errors = $show;
 980		return $errors;
 981	}
 982
 983	/**
 984	 * Disables showing of database errors.
 985	 *
 986	 * By default database errors are not shown.
 987	 *
 988	 * @since 0.71
 989	 * @see wpdb::show_errors()
 990	 *
 991	 * @return bool Whether showing of errors was active
 992	 */
 993	function hide_errors() {
 994		$show = $this->show_errors;
 995		$this->show_errors = false;
 996		return $show;
 997	}
 998
 999	/**
1000	 * Whether to suppress database errors.
1001	 *
1002	 * By default database errors are suppressed, with a simple
1003	 * call to this function they can be enabled.
1004	 *
1005	 * @since 2.5.0
1006	 * @see wpdb::hide_errors()
1007	 * @param bool $suppress Optional. New value. Defaults to true.
1008	 * @return bool Old value
1009	 */
1010	function suppress_errors( $suppress = true ) {
1011		$errors = $this->suppress_errors;
1012		$this->suppress_errors = (bool) $suppress;
1013		return $errors;
1014	}
1015
1016	/**
1017	 * Kill cached query results.
1018	 *
1019	 * @since 0.71
1020	 * @return void
1021	 */
1022	function flush() {
1023		$this->last_result = array();
1024		$this->col_info    = null;
1025		$this->last_query  = null;
1026	}
1027
1028	/**
1029	 * Connect to and select database
1030	 *
1031	 * @since 3.0.0
1032	 */
1033	function db_connect() {
1034
1035		$this->is_mysql = true;
1036
1037		if ( WP_DEBUG ) {
1038			$this->dbh = mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, true );
1039		} else {
1040			$this->dbh = @mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, true );
1041		}
1042
1043		if ( !$this->dbh ) {
1044			wp_load_translations_early();
1045			$this->bail( sprintf( __( "
1046<h1>Error establishing a database connection</h1>
1047<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>
1048<ul>
1049	<li>Are you sure you have the correct username and password?</li>
1050	<li>Are you sure that you have typed the correct hostname?</li>
1051	<li>Are you sure that the database server is running?</li>
1052</ul>
1053<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>
1054" ), htmlspecialchars( $this->dbhost, ENT_QUOTES ) ), 'db_connect_fail' );
1055
1056			return;
1057		}
1058
1059		$this->set_charset( $this->dbh );
1060
1061		$this->ready = true;
1062
1063		$this->select( $this->dbname, $this->dbh );
1064	}
1065
1066	/**
1067	 * Perform a MySQL database query, using current database connection.
1068	 *
1069	 * More information can be found on the codex page.
1070	 *
1071	 * @since 0.71
1072	 *
1073	 * @param string $query Database query
1074	 * @return int|false Number of rows affected/selected or false on error
1075	 */
1076	function query( $query ) {
1077		if ( ! $this->ready )
1078			return false;
1079
1080		// some queries are made before the plugins have been loaded, and thus cannot be filtered with this method
1081		$query = apply_filters( 'query', $query );
1082
1083		$return_val = 0;
1084		$this->flush();
1085
1086		// Log how the function was called
1087		$this->func_call = "\$db->query(\"$query\")";
1088
1089		// Keep track of the last query for debug..
1090		$this->last_query = $query;
1091
1092		if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
1093			$this->timer_start();
1094
1095		$this->result = @mysql_query( $query, $this->dbh );
1096		$this->num_queries++;
1097
1098		if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
1099			$this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
1100
1101		// If there is an error then take note of it..
1102		if ( $this->last_error = mysql_error( $this->dbh ) ) {
1103			$this->print_error();
1104			return false;
1105		}
1106
1107		if ( preg_match( '/^\s*(create|alter|truncate|drop) /i', $query ) ) {
1108			$return_val = $this->result;
1109		} elseif ( preg_match( '/^\s*(insert|delete|update|replace) /i', $query ) ) {
1110			$this->rows_affected = mysql_affected_rows( $this->dbh );
1111			// Take note of the insert_id
1112			if ( preg_match( '/^\s*(insert|replace) /i', $query ) ) {
1113				$this->insert_id = mysql_insert_id($this->dbh);
1114			}
1115			// Return number of rows affected
1116			$return_val = $this->rows_affected;
1117		} else {
1118			$i = 0;
1119			while ( $i < @mysql_num_fields( $this->result ) ) {
1120				$this->col_info[$i] = @mysql_fetch_field( $this->result );
1121				$i++;
1122			}
1123			$num_rows = 0;
1124			while ( $row = @mysql_fetch_object( $this->result ) ) {
1125				$this->last_result[$num_rows] = $row;
1126				$num_rows++;
1127			}
1128
1129			@mysql_free_result( $this->result );
1130
1131			// Log number of rows the query returned
1132			// and return number of rows selected
1133			$this->num_rows = $num_rows;
1134			$return_val     = $num_rows;
1135		}
1136
1137		return $return_val;
1138	}
1139
1140	/**
1141	 * Insert a row into a table.
1142	 *
1143	 * <code>
1144	 * wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
1145	 * wpdb::insert( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
1146	 * </code>
1147	 *
1148	 * @since 2.5.0
1149	 * @see wpdb::prepare()
1150	 * @see wpdb::$field_types
1151	 * @see wp_set_wpdb_vars()
1152	 *
1153	 * @param string $table table name
1154	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1155	 * @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.
1156	 * 	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.
1157	 * @return int|false The number of rows inserted, or false on error.
1158	 */
1159	function insert( $table, $data, $format = null ) {
1160		return $this->_insert_replace_helper( $table, $data, $format, 'INSERT' );
1161	}
1162
1163	/**
1164	 * Replace a row into a table.
1165	 *
1166	 * <code>
1167	 * wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 'bar' ) )
1168	 * wpdb::replace( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( '%s', '%d' ) )
1169	 * </code>
1170	 *
1171	 * @since 3.0.0
1172	 * @see wpdb::prepare()
1173	 * @see wpdb::$field_types
1174	 * @see wp_set_wpdb_vars()
1175	 *
1176	 * @param string $table table name
1177	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1178	 * @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.
1179	 * 	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.
1180	 * @return int|false The number of rows affected, or false on error.
1181	 */
1182	function replace( $table, $data, $format = null ) {
1183		return $this->_insert_replace_helper( $table, $data, $format, 'REPLACE' );
1184	}
1185
1186	/**
1187	 * Helper function for insert and replace.
1188	 *
1189	 * Runs an insert or replace query based on $type argument.
1190	 *
1191	 * @access private
1192	 * @since 3.0.0
1193	 * @see wpdb::prepare()
1194	 * @see wpdb::$field_types
1195	 * @see wp_set_wpdb_vars()
1196	 *
1197	 * @param string $table table name
1198	 * @param array $data Data to insert (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1199	 * @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.
1200	 * 	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.
1201	 * @param string $type Optional. What type of operation is this? INSERT or REPLACE. Defaults to INSERT.
1202	 * @return int|false The number of rows affected, or false on error.
1203	 */
1204	function _insert_replace_helper( $table, $data, $format = null, $type = 'INSERT' ) {
1205		if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) )
1206			return false;
1207		$formats = $format = (array) $format;
1208		$fields = array_keys( $data );
1209		$formatted_fields = array();
1210		foreach ( $fields as $field ) {
1211			if ( !empty( $format ) )
1212				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
1213			elseif ( isset( $this->field_types[$field] ) )
1214				$form = $this->field_types[$field];
1215			else
1216				$form = '%s';
1217			$formatted_fields[] = $form;
1218		}
1219		$sql = "{$type} INTO `$table` (`" . implode( '`,`', $fields ) . "`) VALUES (" . implode( ",", $formatted_fields ) . ")";
1220		return $this->query( $this->prepare( $sql, $data ) );
1221	}
1222
1223	/**
1224	 * Update a row in the table
1225	 *
1226	 * <code>
1227	 * wpdb::update( 'table', array( 'column' => 'foo', 'field' => 'bar' ), array( 'ID' => 1 ) )
1228	 * wpdb::update( 'table', array( 'column' => 'foo', 'field' => 1337 ), array( 'ID' => 1 ), array( '%s', '%d' ), array( '%d' ) )
1229	 * </code>
1230	 *
1231	 * @since 2.5.0
1232	 * @see wpdb::prepare()
1233	 * @see wpdb::$field_types
1234	 * @see wp_set_wpdb_vars()
1235	 *
1236	 * @param string $table table name
1237	 * @param array $data Data to update (in column => value pairs). Both $data columns and $data values should be "raw" (neither should be SQL escaped).
1238	 * @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".
1239	 * @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.
1240	 * 	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.
1241	 * @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.
1242	 * @return int|false The number of rows updated, or false on error.
1243	 */
1244	function update( $table, $data, $where, $format = null, $where_format = null ) {
1245		if ( ! is_array( $data ) || ! is_array( $where ) )
1246			return false;
1247
1248		$formats = $format = (array) $format;
1249		$bits = $wheres = array();
1250		foreach ( (array) array_keys( $data ) as $field ) {
1251			if ( !empty( $format ) )
1252				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
1253			elseif ( isset($this->field_types[$field]) )
1254				$form = $this->field_types[$field];
1255			else
1256				$form = '%s';
1257			$bits[] = "`$field` = {$form}";
1258		}
1259
1260		$where_formats = $where_format = (array) $where_format;
1261		foreach ( (array) array_keys( $where ) as $field ) {
1262			if ( !empty( $where_format ) )
1263				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
1264			elseif ( isset( $this->field_types[$field] ) )
1265				$form = $this->field_types[$field];
1266			else
1267				$form = '%s';
1268			$wheres[] = "`$field` = {$form}";
1269		}
1270
1271		$sql = "UPDATE `$table` SET " . implode( ', ', $bits ) . ' WHERE ' . implode( ' AND ', $wheres );
1272		return $this->query( $this->prepare( $sql, array_merge( array_values( $data ), array_values( $where ) ) ) );
1273	}
1274
1275	/**
1276	 * Delete a row in the table
1277	 *
1278	 * <code>
1279	 * wpdb::delete( 'table', array( 'ID' => 1 ) )
1280	 * wpdb::delete( 'table', array( 'ID' => 1 ), array( '%d' ) )
1281	 * </code>
1282	 *
1283	 * @since 3.4.0
1284	 * @see wpdb::prepare()
1285	 * @see wpdb::$field_types
1286	 * @see wp_set_wpdb_vars()
1287	 *
1288	 * @param string $table table name
1289	 * @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".
1290	 * @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.
1291	 * @return int|false The number of rows updated, or false on error.
1292	 */
1293	function delete( $table, $where, $where_format = null ) {
1294		if ( ! is_array( $where ) )
1295			return false;
1296
1297		$bits = $wheres = array();
1298
1299		$where_formats = $where_format = (array) $where_format;
1300
1301		foreach ( array_keys( $where ) as $field ) {
1302			if ( !empty( $where_format ) ) {
1303				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
1304			} elseif ( isset( $this->field_types[ $field ] ) ) {
1305				$form = $this->field_types[ $field ];
1306			} else {
1307				$form = '%s';
1308			}
1309
1310			$wheres[] = "$field = $form";
1311		}
1312
1313		$sql = "DELETE FROM $table WHERE " . implode( ' AND ', $wheres );
1314		return $this->query( $this->prepare( $sql, $where ) );
1315	}
1316
1317
1318	/**
1319	 * Retrieve one variable from the database.
1320	 *
1321	 * Executes a SQL query and returns the value from the SQL result.
1322	 * 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.
1323	 * If $query is null, this function returns the value in the specified column and row from the previous SQL result.
1324	 *
1325	 * @since 0.71
1326	 *
1327	 * @param string|null $query Optional. SQL query. Defaults to null, use the result from the previous query.
1328	 * @param int $x Optional. Column of value to return. Indexed from 0.
1329	 * @param int $y Optional. Row of value to return. Indexed from 0.
1330	 * @return string|null Database query result (as string), or null on failure
1331	 */
1332	function get_var( $query = null, $x = 0, $y = 0 ) {
1333		$this->func_call = "\$db->get_var(\"$query\", $x, $y)";
1334		if ( $query )
1335			$this->query( $query );
1336
1337		// Extract var out of cached results based x,y vals
1338		if ( !empty( $this->last_result[$y] ) ) {
1339			$values = array_values( get_object_vars( $this->last_result[$y] ) );
1340		}
1341
1342		// If there is a value return it else return null
1343		return ( isset( $values[$x] ) && $values[$x] !== '' ) ? $values[$x] : null;
1344	}
1345
1346	/**
1347	 * Retrieve one row from the database.
1348	 *
1349	 * Executes a SQL query and returns the row from the SQL result.
1350	 *
1351	 * @since 0.71
1352	 *
1353	 * @param string|null $query SQL query.
1354	 * @param string $output Optional. one of ARRAY_A | ARRAY_N | OBJECT constants. Return an associative array (column => value, ...),
1355	 * 	a numerically indexed array (0 => value, ...) or an object ( ->column = value ), respectively.
1356	 * @param int $y Optional. Row to return. Indexed from 0.
1357	 * @return mixed Database query result in format specified by $output or null on failure
1358	 */
1359	function get_row( $query = null, $output = OBJECT, $y = 0 ) {
1360		$this->func_call = "\$db->get_row(\"$query\",$output,$y)";
1361		if ( $query )
1362			$this->query( $query );
1363		else
1364			return null;
1365
1366		if ( !isset( $this->last_result[$y] ) )
1367			return null;
1368
1369		if ( $output == OBJECT ) {
1370			return $this->last_result[$y] ? $this->last_result[$y] : null;
1371		} elseif ( $output == ARRAY_A ) {
1372			return $this->last_result[$y] ? get_object_vars( $this->last_result[$y] ) : null;
1373		} elseif ( $output == ARRAY_N ) {
1374			return $this->last_result[$y] ? array_values( get_object_vars( $this->last_result[$y] ) ) : null;
1375		} else {
1376			$this->print_error( " \$db->get_row(string query, output type, int offset) -- Output type must be one of: OBJECT, ARRAY_A, ARRAY_N" );
1377		}
1378	}
1379
1380	/**
1381	 * Retrieve one column from the database.
1382	 *
1383	 * Executes a SQL query and returns the column from the SQL result.
1384	 * If the SQL result contains more than one column, this function returns the column specified.
1385	 * If $query is null, this function returns the specified column from the previous SQL result.
1386	 *
1387	 * @since 0.71
1388	 *
1389	 * @param string|null $query Optional. SQL query. Defaults to previous query.
1390	 * @param int $x Optional. Column to return. Indexed from 0.
1391	 * @return array Database query result. Array indexed from 0 by SQL result row number.
1392	 */
1393	function get_col( $query = null , $x = 0 ) {
1394		if ( $query )
1395			$this->query( $query );
1396
1397		$new_array = array();
1398		// Extract the column values
1399		for ( $i = 0, $j = count( $this->last_result ); $i < $j; $i++ ) {
1400			$new_array[$i] = $this->get_var( null, $x, $i );
1401		}
1402		return $new_array;
1403	}
1404
1405	/**
1406	 * Retrieve an entire SQL result set from the database (i.e., many rows)
1407	 *
1408	 * Executes a SQL query and returns the entire SQL result.
1409	 *
1410	 * @since 0.71
1411	 *
1412	 * @param string $query SQL query.
1413	 * @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.
1414	 * 	Each row is an associative array (column => value, ...), a numerically indexed array (0 => value, ...), or an object. ( ->column = value ), respectively.
1415	 * 	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.
1416	 * @return mixed Database query results
1417	 */
1418	function get_results( $query = null, $output = OBJECT ) {
1419		$this->func_call = "\$db->get_results(\"$query\", $output)";
1420
1421		if ( $query )
1422			$this->query( $query );
1423		else
1424			return null;
1425
1426		$new_array = array();
1427		if ( $output == OBJECT ) {
1428			// Return an integer-keyed array of row objects
1429			return $this->last_result;
1430		} elseif ( $output == OBJECT_K ) {
1431			// Return an array of row objects with keys from column 1
1432			// (Duplicates are discarded)
1433			foreach ( $this->last_result as $row ) {
1434				$var_by_ref = get_object_vars( $row );
1435				$key = array_shift( $var_by_ref );
1436				if ( ! isset( $new_array[ $key ] ) )
1437					$new_array[ $key ] = $row;
1438			}
1439			return $new_array;
1440		} elseif ( $output == ARRAY_A || $output == ARRAY_N ) {
1441			// Return an integer-keyed array of...
1442			if ( $this->last_result ) {
1443				foreach( (array) $this->last_result as $row ) {
1444					if ( $output == ARRAY_N ) {
1445						// ...integer-keyed row arrays
1446						$new_array[] = array_values( get_object_vars( $row ) );
1447					} else {
1448						// ...column name-keyed row arrays
1449						$new_array[] = get_object_vars( $row );
1450					}
1451				}
1452			}
1453			return $new_array;
1454		}
1455		return null;
1456	}
1457
1458	/**
1459	 * Retrieve column metadata from the last query.
1460	 *
1461	 * @since 0.71
1462	 *
1463	 * @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
1464	 * @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
1465	 * @return mixed Column Results
1466	 */
1467	function get_col_info( $info_type = 'name', $col_offset = -1 ) {
1468		if ( $this->col_info ) {
1469			if ( $col_offset == -1 ) {
1470				$i = 0;
1471				$new_array = array();
1472				foreach( (array) $this->col_info as $col ) {
1473					$new_array[$i] = $col->{$info_type};
1474					$i++;
1475				}
1476				return $new_array;
1477			} else {
1478				return $this->col_info[$col_offset]->{$info_type};
1479			}
1480		}
1481	}
1482
1483	/**
1484	 * Starts the timer, for debugging purposes.
1485	 *
1486	 * @since 1.5.0
1487	 *
1488	 * @return true
1489	 */
1490	function timer_start() {
1491		$this->time_start = microtime( true );
1492		return true;
1493	}
1494
1495	/**
1496	 * Stops the debugging timer.
1497	 *
1498	 * @since 1.5.0
1499	 *
1500	 * @return float Total time spent on the query, in seconds
1501	 */
1502	function timer_stop() {
1503		return ( microtime( true ) - $this->time_start );
1504	}
1505
1506	/**
1507	 * Wraps errors in a nice header and footer and dies.
1508	 *
1509	 * Will not die if wpdb::$show_errors is true
1510	 *
1511	 * @since 1.5.0
1512	 *
1513	 * @param string $message The Error message
1514	 * @param string $error_code Optional. A Computer readable string to identify the error.
1515	 * @return false|void
1516	 */
1517	function bail( $message, $error_code = '500' ) {
1518		if ( !$this->show_errors ) {
1519			if ( class_exists( 'WP_Error' ) )
1520				$this->error = new WP_Error($error_code, $message);
1521			else
1522				$this->error = $message;
1523			return false;
1524		}
1525		wp_die($message);
1526	}
1527
1528	/**
1529	 * Whether MySQL database is at least the required minimum version.
1530	 *
1531	 * @since 2.5.0
1532	 * @uses $wp_version
1533	 * @uses $required_mysql_version
1534	 *
1535	 * @return WP_Error
1536	 */
1537	function check_database_version() {
1538		global $wp_version, $required_mysql_version;
1539		// Make sure the server has the required MySQL version
1540		if ( version_compare($this->db_version(), $required_mysql_version, '<') )
1541			return new WP_Error('database_version', sprintf( __( '<strong>ERROR</strong>: WordPress %1$s requires MySQL %2$s or higher' ), $wp_version, $required_mysql_version ));
1542	}
1543
1544	/**
1545	 * Whether the database supports collation.
1546	 *
1547	 * Called when WordPress is generating the table scheme.
1548	 *
1549	 * @since 2.5.0
1550	 *
1551	 * @return bool True if collation is supported, false if version does not
1552	 */
1553	function supports_collation() {
1554		return $this->has_cap( 'collation' );
1555	}
1556
1557	/**
1558	 * Determine if a database supports a particular feature
1559	 *
1560	 * @since 2.7.0
1561	 * @see   wpdb::db_version()
1562	 *
1563	 * @param string $db_cap the feature
1564	 * @return bool
1565	 */
1566	function has_cap( $db_cap ) {
1567		$version = $this->db_version();
1568
1569		switch ( strtolower( $db_cap ) ) {
1570			case 'collation' :    // @since 2.5.0
1571			case 'group_concat' : // @since 2.7
1572			case 'subqueries' :   // @since 2.7
1573				return version_compare( $version, '4.1', '>=' );
1574			case 'set_charset' :
1575				return version_compare($version, '5.0.7', '>=');
1576		};
1577
1578		return false;
1579	}
1580
1581	/**
1582	 * Retrieve the name of the function that called wpdb.
1583	 *
1584	 * Searches up the list of functions until it reaches
1585	 * the one that would most logically had called this method.
1586	 *
1587	 * @since 2.5.0
1588	 *
1589	 * @return string The name of the calling function
1590	 */
1591	function get_caller() {
1592		return wp_debug_backtrace_summary( __CLASS__ );
1593	}
1594
1595	/**
1596	 * The database version number.
1597	 *
1598	 * @since 2.7.0
1599	 *
1600	 * @return false|string false on failure, version number on success
1601	 */
1602	function db_version() {
1603		return preg_replace( '/[^0-9.].*/', '', mysql_get_server_info( $this->dbh ) );
1604	}
1605}