mysqli.php 24.3 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014
<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Database
 *
 * @copyright   Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * MySQLi database driver
 *
 * @link   https://www.php.net/manual/en/book.mysqli.php
 * @since  3.0.0
 */
class JDatabaseDriverMysqli extends JDatabaseDriver
{
	/**
	 * The name of the database driver.
	 *
	 * @var    string
	 * @since  3.0.0
	 */
	public $name = 'mysqli';

	/**
	 * The type of the database server family supported by this driver.
	 *
	 * @var    string
	 * @since  CMS 3.5.0
	 */
	public $serverType = 'mysql';

	/**
	 * @var    mysqli  The database connection resource.
	 * @since  1.7.0
	 */
	protected $connection;

	/**
	 * The character(s) used to quote SQL statement names such as table names or field names,
	 * etc. The child classes should define this as necessary.  If a single character string the
	 * same character is used for both sides of the quoted name, else the first character will be
	 * used for the opening quote and the second for the closing quote.
	 *
	 * @var    string
	 * @since  3.0.1
	 */
	protected $nameQuote = '`';

	/**
	 * The null or zero representation of a timestamp for the database driver.  This should be
	 * defined in child classes to hold the appropriate value for the engine.
	 *
	 * @var    string
	 * @since  3.0.1
	 */
	protected $nullDate = '0000-00-00 00:00:00';

	/**
	 * @var    string  The minimum supported database version.
	 * @since  3.0.1
	 */
	protected static $dbMinimum = '5.0.4';

	/**
	 * Constructor.
	 *
	 * @param   array  $options  List of options used to configure the connection
	 *
	 * @since   3.0.0
	 */
	public function __construct($options)
	{
		// Get some basic values from the options.
		$options['host']     = (isset($options['host'])) ? $options['host'] : 'localhost';
		$options['user']     = (isset($options['user'])) ? $options['user'] : '';
		$options['password'] = (isset($options['password'])) ? $options['password'] : '';
		$options['database'] = (isset($options['database'])) ? $options['database'] : '';
		$options['select']   = (isset($options['select'])) ? (bool) $options['select'] : true;
		$options['port']     = (isset($options['port'])) ? (int) $options['port'] : null;
		$options['socket']   = (isset($options['socket'])) ? $options['socket'] : null;

		// Finalize initialisation.
		parent::__construct($options);
	}

	/**
	 * Connects to the database if needed.
	 *
	 * @return  void  Returns void if the database connected successfully.
	 *
	 * @since   3.0.0
	 * @throws  RuntimeException
	 */
	public function connect()
	{
		if ($this->connection)
		{
			return;
		}

		/*
		 * Unlike mysql_connect(), mysqli_connect() takes the port and socket as separate arguments. Therefore, we
		 * have to extract them from the host string.
		 */
		$port = isset($this->options['port']) ? $this->options['port'] : 3306;
		$regex = '/^(?P<host>((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))(:(?P<port>.+))?$/';

		if (preg_match($regex, $this->options['host'], $matches))
		{
			// It's an IPv4 address with or without port
			$this->options['host'] = $matches['host'];

			if (!empty($matches['port']))
			{
				$port = $matches['port'];
			}
		}
		elseif (preg_match('/^(?P<host>\[.*\])(:(?P<port>.+))?$/', $this->options['host'], $matches))
		{
			// We assume square-bracketed IPv6 address with or without port, e.g. [fe80:102::2%eth1]:3306
			$this->options['host'] = $matches['host'];

			if (!empty($matches['port']))
			{
				$port = $matches['port'];
			}
		}
		elseif (preg_match('/^(?P<host>(\w+:\/{2,3})?[a-z0-9\.\-]+)(:(?P<port>[^:]+))?$/i', $this->options['host'], $matches))
		{
			// Named host (e.g example.com or localhost) with or without port
			$this->options['host'] = $matches['host'];

			if (!empty($matches['port']))
			{
				$port = $matches['port'];
			}
		}
		elseif (preg_match('/^:(?P<port>[^:]+)$/', $this->options['host'], $matches))
		{
			// Empty host, just port, e.g. ':3306'
			$this->options['host'] = 'localhost';
			$port = $matches['port'];
		}
		// ... else we assume normal (naked) IPv6 address, so host and port stay as they are or default

		// Get the port number or socket name
		if (is_numeric($port))
		{
			$this->options['port'] = (int) $port;
		}
		else
		{
			$this->options['socket'] = $port;
		}

		// Make sure the MySQLi extension for PHP is installed and enabled.
		if (!self::isSupported())
		{
			throw new JDatabaseExceptionUnsupported('The MySQLi extension for PHP is not installed or enabled.');
		}

		$this->connection = @mysqli_connect(
			$this->options['host'], $this->options['user'], $this->options['password'], null, $this->options['port'], $this->options['socket']
		);

		// Attempt to connect to the server.
		if (!$this->connection)
		{
			throw new JDatabaseExceptionConnecting('Could not connect to MySQL server.');
		}

		// Set sql_mode to non_strict mode
		mysqli_query($this->connection, "SET @@SESSION.sql_mode = '';");

		// If auto-select is enabled select the given database.
		if ($this->options['select'] && !empty($this->options['database']))
		{
			$this->select($this->options['database']);
		}

		// Pre-populate the UTF-8 Multibyte compatibility flag based on server version
		$this->utf8mb4 = $this->serverClaimsUtf8mb4Support();

		// Set the character set (needed for MySQL 4.1.2+).
		$this->utf = $this->setUtf();

		// Disable query cache and turn profiling ON in debug mode.
		if ($this->debug)
		{
			mysqli_query($this->connection, 'SET query_cache_type = 0;');

			if ($this->hasProfiling())
			{
				mysqli_query($this->connection, 'SET profiling_history_size = 100, profiling = 1;');
			}
		}
	}

	/**
	 * Disconnects the database.
	 *
	 * @return  void
	 *
	 * @since   3.0.0
	 */
	public function disconnect()
	{
		// Close the connection.
		if ($this->connection instanceof mysqli && $this->connection->stat() !== false)
		{
			foreach ($this->disconnectHandlers as $h)
			{
				call_user_func_array($h, array( &$this));
			}

			mysqli_close($this->connection);
		}

		$this->connection = null;
	}

	/**
	 * Method to escape a string for usage in an SQL statement.
	 *
	 * @param   string   $text   The string to be escaped.
	 * @param   boolean  $extra  Optional parameter to provide extra escaping.
	 *
	 * @return  string  The escaped string.
	 *
	 * @since   3.0.0
	 */
	public function escape($text, $extra = false)
	{
		if (is_int($text))
		{
			return $text;
		}

		if (is_float($text))
		{
			// Force the dot as a decimal point.
			return str_replace(',', '.', $text);
		}

		$this->connect();

		$result = mysqli_real_escape_string($this->getConnection(), $text);

		if ($extra)
		{
			$result = addcslashes($result, '%_');
		}

		return $result;
	}

	/**
	 * Test to see if the MySQL connector is available.
	 *
	 * @return  boolean  True on success, false otherwise.
	 *
	 * @since   3.0.0
	 */
	public static function isSupported()
	{
		return function_exists('mysqli_connect');
	}

	/**
	 * Determines if the connection to the server is active.
	 *
	 * @return  boolean  True if connected to the database engine.
	 *
	 * @since   3.0.0
	 */
	public function connected()
	{
		if (is_object($this->connection))
		{
			return mysqli_ping($this->connection);
		}

		return false;
	}

	/**
	 * Drops a table from the database.
	 *
	 * @param   string   $tableName  The name of the database table to drop.
	 * @param   boolean  $ifExists   Optionally specify that the table must exist before it is dropped.
	 *
	 * @return  JDatabaseDriverMysqli  Returns this object to support chaining.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function dropTable($tableName, $ifExists = true)
	{
		$this->connect();

		$query = $this->getQuery(true);

		$this->setQuery('DROP TABLE ' . ($ifExists ? 'IF EXISTS ' : '') . $query->quoteName($tableName));

		$this->execute();

		return $this;
	}

	/**
	 * Get the number of affected rows by the last INSERT, UPDATE, REPLACE or DELETE for the previous executed SQL statement.
	 *
	 * @return  integer  The number of affected rows.
	 *
	 * @since   3.0.0
	 */
	public function getAffectedRows()
	{
		$this->connect();

		return mysqli_affected_rows($this->connection);
	}

	/**
	 * Method to get the database collation.
	 *
	 * @return  mixed  The collation in use by the database (string) or boolean false if not supported.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function getCollation()
	{
		$this->connect();

		// Attempt to get the database collation by accessing the server system variable.
		$this->setQuery('SHOW VARIABLES LIKE "collation_database"');
		$result = $this->loadObject();

		if (property_exists($result, 'Value'))
		{
			return $result->Value;
		}
		else
		{
			return false;
		}
	}

	/**
	 * Method to get the database connection collation, as reported by the driver. If the connector doesn't support
	 * reporting this value please return an empty string.
	 *
	 * @return  string
	 */
	public function getConnectionCollation()
	{
		$this->connect();

		// Attempt to get the database collation by accessing the server system variable.
		$this->setQuery('SHOW VARIABLES LIKE "collation_connection"');
		$result = $this->loadObject();

		if (property_exists($result, 'Value'))
		{
			return $result->Value;
		}
		else
		{
			return false;
		}
	}

	/**
	 * Get the number of returned rows for the previous executed SQL statement.
	 * This command is only valid for statements like SELECT or SHOW that return an actual result set.
	 * To retrieve the number of rows affected by an INSERT, UPDATE, REPLACE or DELETE query, use getAffectedRows().
	 *
	 * @param   resource  $cursor  An optional database cursor resource to extract the row count from.
	 *
	 * @return  integer   The number of returned rows.
	 *
	 * @since   3.0.0
	 */
	public function getNumRows($cursor = null)
	{
		return mysqli_num_rows($cursor ? $cursor : $this->cursor);
	}

	/**
	 * Shows the table CREATE statement that creates the given tables.
	 *
	 * @param   mixed  $tables  A table name or a list of table names.
	 *
	 * @return  array  A list of the create SQL for the tables.
	 *
	 * @since   3.0.0
	 * @throws  RuntimeException
	 */
	public function getTableCreate($tables)
	{
		$this->connect();

		$result = array();

		// Sanitize input to an array and iterate over the list.
		settype($tables, 'array');

		foreach ($tables as $table)
		{
			// Set the query to get the table CREATE statement.
			$this->setQuery('SHOW CREATE table ' . $this->quoteName($this->escape($table)));
			$row = $this->loadRow();

			// Populate the result array based on the create statements.
			$result[$table] = $row[1];
		}

		return $result;
	}

	/**
	 * Retrieves field information about a given table.
	 *
	 * @param   string   $table     The name of the database table.
	 * @param   boolean  $typeOnly  True to only return field types.
	 *
	 * @return  array  An array of fields for the database table.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function getTableColumns($table, $typeOnly = true)
	{
		$this->connect();

		$result = array();

		// Set the query to get the table fields statement.
		$this->setQuery('SHOW FULL COLUMNS FROM ' . $this->quoteName($this->escape($table)));
		$fields = $this->loadObjectList();

		// If we only want the type as the value add just that to the list.
		if ($typeOnly)
		{
			foreach ($fields as $field)
			{
				$result[$field->Field] = preg_replace('/[(0-9)]/', '', $field->Type);
			}
		}
		// If we want the whole field data object add that to the list.
		else
		{
			foreach ($fields as $field)
			{
				$result[$field->Field] = $field;
			}
		}

		return $result;
	}

	/**
	 * Get the details list of keys for a table.
	 *
	 * @param   string  $table  The name of the table.
	 *
	 * @return  array  An array of the column specification for the table.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function getTableKeys($table)
	{
		$this->connect();

		// Get the details columns information.
		$this->setQuery('SHOW KEYS FROM ' . $this->quoteName($table));
		$keys = $this->loadObjectList();

		return $keys;
	}

	/**
	 * Method to get an array of all tables in the database.
	 *
	 * @return  array  An array of all the tables in the database.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function getTableList()
	{
		$this->connect();

		// Set the query to get the tables statement.
		$this->setQuery('SHOW TABLES');
		$tables = $this->loadColumn();

		return $tables;
	}

	/**
	 * Get the version of the database connector.
	 *
	 * @return  string  The database connector version.
	 *
	 * @since   3.0.0
	 */
	public function getVersion()
	{
		$this->connect();

		return mysqli_get_server_info($this->connection);
	}

	/**
	 * Method to get the auto-incremented value from the last INSERT statement.
	 *
	 * @return  mixed  The value of the auto-increment field from the last inserted row.
	 *                 If the value is greater than maximal int value, it will return a string.
	 *
	 * @since   3.0.0
	 */
	public function insertid()
	{
		$this->connect();

		return mysqli_insert_id($this->connection);
	}

	/**
	 * Locks a table in the database.
	 *
	 * @param   string  $table  The name of the table to unlock.
	 *
	 * @return  JDatabaseDriverMysqli  Returns this object to support chaining.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function lockTable($table)
	{
		$this->setQuery('LOCK TABLES ' . $this->quoteName($table) . ' WRITE')->execute();

		return $this;
	}

	/**
	 * Execute the SQL statement.
	 *
	 * @return  mixed  A database cursor resource on success, boolean false on failure.
	 *
	 * @since   3.0.0
	 * @throws  RuntimeException
	 */
	public function execute()
	{
		$this->connect();

		// Take a local copy so that we don't modify the original query and cause issues later
		$query = $this->replacePrefix((string) $this->sql);

		if (!($this->sql instanceof JDatabaseQuery) && ($this->limit > 0 || $this->offset > 0))
		{
			$query .= ' LIMIT ' . $this->offset . ', ' . $this->limit;
		}

		if (!is_object($this->connection))
		{
			JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'database');
			throw new JDatabaseExceptionExecuting($query, $this->errorMsg, $this->errorNum);
		}

		// Increment the query counter.
		$this->count++;

		// Reset the error values.
		$this->errorNum = 0;
		$this->errorMsg = '';
		$memoryBefore   = null;

		// If debugging is enabled then let's log the query.
		if ($this->debug)
		{
			// Add the query to the object queue.
			$this->log[] = $query;

			JLog::add($query, JLog::DEBUG, 'databasequery');

			$this->timings[] = microtime(true);

			if (is_object($this->cursor))
			{
				// Avoid warning if result already freed by third-party library
				@$this->freeResult();
			}

			$memoryBefore = memory_get_usage();
		}

		// Execute the query. Error suppression is used here to prevent warnings/notices that the connection has been lost.
		$this->cursor = @mysqli_query($this->connection, $query);

		if ($this->debug)
		{
			$this->timings[] = microtime(true);

			if (defined('DEBUG_BACKTRACE_IGNORE_ARGS'))
			{
				$this->callStacks[] = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
			}
			else
			{
				$this->callStacks[] = debug_backtrace();
			}

			$this->callStacks[count($this->callStacks) - 1][0]['memory'] = array(
				$memoryBefore,
				memory_get_usage(),
				is_object($this->cursor) ? $this->getNumRows() : null,
			);
		}

		// If an error occurred handle it.
		if (!$this->cursor)
		{
			// Get the error number and message before we execute any more queries.
			$this->errorNum = $this->getErrorNumber();
			$this->errorMsg = $this->getErrorMessage();

			// Check if the server was disconnected.
			if (!$this->connected())
			{
				try
				{
					// Attempt to reconnect.
					$this->connection = null;
					$this->connect();
				}
				// If connect fails, ignore that exception and throw the normal exception.
				catch (RuntimeException $e)
				{
					// Get the error number and message.
					$this->errorNum = $this->getErrorNumber();
					$this->errorMsg = $this->getErrorMessage();

					JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'database-error');

					throw new JDatabaseExceptionExecuting($query, $this->errorMsg, $this->errorNum, $e);
				}

				// Since we were able to reconnect, run the query again.
				return $this->execute();
			}
			// The server was not disconnected.
			else
			{
				JLog::add(JText::sprintf('JLIB_DATABASE_QUERY_FAILED', $this->errorNum, $this->errorMsg), JLog::ERROR, 'database-error');

				throw new JDatabaseExceptionExecuting($query, $this->errorMsg, $this->errorNum);
			}
		}

		return $this->cursor;
	}

	/**
	 * Renames a table in the database.
	 *
	 * @param   string  $oldTable  The name of the table to be renamed
	 * @param   string  $newTable  The new name for the table.
	 * @param   string  $backup    Not used by MySQL.
	 * @param   string  $prefix    Not used by MySQL.
	 *
	 * @return  JDatabaseDriverMysqli  Returns this object to support chaining.
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function renameTable($oldTable, $newTable, $backup = null, $prefix = null)
	{
		$this->setQuery('RENAME TABLE ' . $oldTable . ' TO ' . $newTable)->execute();

		return $this;
	}

	/**
	 * Select a database for use.
	 *
	 * @param   string  $database  The name of the database to select for use.
	 *
	 * @return  boolean  True if the database was successfully selected.
	 *
	 * @since   3.0.0
	 * @throws  RuntimeException
	 */
	public function select($database)
	{
		$this->connect();

		if (!$database)
		{
			return false;
		}

		if (!mysqli_select_db($this->connection, $database))
		{
			throw new JDatabaseExceptionConnecting('Could not connect to MySQL database.');
		}

		return true;
	}

	/**
	 * Set the connection to use UTF-8 character encoding.
	 *
	 * @return  boolean  True on success.
	 *
	 * @since   3.0.0
	 */
	public function setUtf()
	{
		// If UTF is not supported return false immediately
		if (!$this->utf)
		{
			return false;
		}

		// Make sure we're connected to the server
		$this->connect();

		// Which charset should I use, plain utf8 or multibyte utf8mb4?
		$charset = $this->utf8mb4 ? 'utf8mb4' : 'utf8';

		$result = @$this->connection->set_charset($charset);

		/**
		 * If I could not set the utf8mb4 charset then the server doesn't support utf8mb4 despite claiming otherwise.
		 * This happens on old MySQL server versions (less than 5.5.3) using the mysqlnd PHP driver. Since mysqlnd
		 * masks the server version and reports only its own we can not be sure if the server actually does support
		 * UTF-8 Multibyte (i.e. it's MySQL 5.5.3 or later). Since the utf8mb4 charset is undefined in this case we
		 * catch the error and determine that utf8mb4 is not supported!
		 */
		if (!$result && $this->utf8mb4)
		{
			$this->utf8mb4 = false;
			$result = @$this->connection->set_charset('utf8');
		}

		return $result;
	}

	/**
	 * Method to commit a transaction.
	 *
	 * @param   boolean  $toSavepoint  If true, commit to the last savepoint.
	 *
	 * @return  void
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function transactionCommit($toSavepoint = false)
	{
		$this->connect();

		if (!$toSavepoint || $this->transactionDepth <= 1)
		{
			if ($this->setQuery('COMMIT')->execute())
			{
				$this->transactionDepth = 0;
			}

			return;
		}

		$this->transactionDepth--;
	}

	/**
	 * Method to roll back a transaction.
	 *
	 * @param   boolean  $toSavepoint  If true, rollback to the last savepoint.
	 *
	 * @return  void
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function transactionRollback($toSavepoint = false)
	{
		$this->connect();

		if (!$toSavepoint || $this->transactionDepth <= 1)
		{
			if ($this->setQuery('ROLLBACK')->execute())
			{
				$this->transactionDepth = 0;
			}

			return;
		}

		$savepoint = 'SP_' . ($this->transactionDepth - 1);
		$this->setQuery('ROLLBACK TO SAVEPOINT ' . $this->quoteName($savepoint));

		if ($this->execute())
		{
			$this->transactionDepth--;
		}
	}

	/**
	 * Method to initialize a transaction.
	 *
	 * @param   boolean  $asSavepoint  If true and a transaction is already active, a savepoint will be created.
	 *
	 * @return  void
	 *
	 * @since   3.0.1
	 * @throws  RuntimeException
	 */
	public function transactionStart($asSavepoint = false)
	{
		$this->connect();

		if (!$asSavepoint || !$this->transactionDepth)
		{
			if ($this->setQuery('START TRANSACTION')->execute())
			{
				$this->transactionDepth = 1;
			}

			return;
		}

		$savepoint = 'SP_' . $this->transactionDepth;
		$this->setQuery('SAVEPOINT ' . $this->quoteName($savepoint));

		if ($this->execute())
		{
			$this->transactionDepth++;
		}
	}

	/**
	 * Method to fetch a row from the result set cursor as an array.
	 *
	 * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
	 *
	 * @return  mixed  Either the next row from the result set or false if there are no more rows.
	 *
	 * @since   3.0.0
	 */
	protected function fetchArray($cursor = null)
	{
		return mysqli_fetch_row($cursor ? $cursor : $this->cursor);
	}

	/**
	 * Method to fetch a row from the result set cursor as an associative array.
	 *
	 * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
	 *
	 * @return  mixed  Either the next row from the result set or false if there are no more rows.
	 *
	 * @since   3.0.0
	 */
	protected function fetchAssoc($cursor = null)
	{
		return mysqli_fetch_assoc($cursor ? $cursor : $this->cursor);
	}

	/**
	 * Method to fetch a row from the result set cursor as an object.
	 *
	 * @param   mixed   $cursor  The optional result set cursor from which to fetch the row.
	 * @param   string  $class   The class name to use for the returned row object.
	 *
	 * @return  mixed   Either the next row from the result set or false if there are no more rows.
	 *
	 * @since   3.0.0
	 */
	protected function fetchObject($cursor = null, $class = 'stdClass')
	{
		return mysqli_fetch_object($cursor ? $cursor : $this->cursor, $class);
	}

	/**
	 * Method to free up the memory used for the result set.
	 *
	 * @param   mixed  $cursor  The optional result set cursor from which to fetch the row.
	 *
	 * @return  void
	 *
	 * @since   3.0.0
	 */
	protected function freeResult($cursor = null)
	{
		mysqli_free_result($cursor ? $cursor : $this->cursor);

		if ((! $cursor) || ($cursor === $this->cursor))
		{
			$this->cursor = null;
		}
	}

	/**
	 * Unlocks tables in the database.
	 *
	 * @return  JDatabaseDriverMysqli  Returns this object to support chaining.
	 *
	 * @since   3.0.0
	 * @throws  RuntimeException
	 */
	public function unlockTables()
	{
		$this->setQuery('UNLOCK TABLES')->execute();

		return $this;
	}

	/**
	 * Internal function to check if profiling is available
	 *
	 * @return  boolean
	 *
	 * @since   3.1.3
	 */
	private function hasProfiling()
	{
		try
		{
			$res = mysqli_query($this->connection, "SHOW VARIABLES LIKE 'have_profiling'");
			$row = mysqli_fetch_assoc($res);

			return isset($row);
		}
		catch (Exception $e)
		{
			return false;
		}
	}

	/**
	 * Does the database server claim to have support for UTF-8 Multibyte (utf8mb4) collation?
	 *
	 * libmysql supports utf8mb4 since 5.5.3 (same version as the MySQL server). mysqlnd supports utf8mb4 since 5.0.9.
	 *
	 * @return  boolean
	 *
	 * @since   CMS 3.5.0
	 */
	private function serverClaimsUtf8mb4Support()
	{
		$client_version = mysqli_get_client_info();
		$server_version = $this->getVersion();

		if (version_compare($server_version, '5.5.3', '<'))
		{
			return false;
		}
		else
		{
			if (strpos($client_version, 'mysqlnd') !== false)
			{
				$client_version = preg_replace('/^\D+([\d.]+).*/', '$1', $client_version);

				return version_compare($client_version, '5.0.9', '>=');
			}
			else
			{
				return version_compare($client_version, '5.5.3', '>=');
			}
		}
	}

	/**
	 * Return the actual SQL Error number
	 *
	 * @return  integer  The SQL Error number
	 *
	 * @since   3.4.6
	 */
	protected function getErrorNumber()
	{
		return (int) mysqli_errno($this->connection);
	}

	/**
	 * Return the actual SQL Error message
	 *
	 * @return  string  The SQL Error message
	 *
	 * @since   3.4.6
	 */
	protected function getErrorMessage()
	{
		$errorMessage = (string) mysqli_error($this->connection);

		// Replace the Databaseprefix with `#__` if we are not in Debug
		if (!$this->debug)
		{
			$errorMessage = str_replace($this->tablePrefix, '#__', $errorMessage);
		}

		return $errorMessage;
	}
}