class DatabaseConnection_mysql


Expanded class hierarchy of DatabaseConnection_mysql

Related topics


drupal/includes/database/mysql/, line 13
Database interface code for MySQL database servers.

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class DatabaseConnection_mysql extends DatabaseConnection {

   * Flag to indicate if the cleanup function in __destruct() should run.
   * @var boolean
  protected $needsCleanup = FALSE;
  public function __construct(array $connection_options = array()) {

    // This driver defaults to transaction support, except if explicitly passed FALSE.
    $this->transactionSupport = !isset($connection_options['transactions']) || $connection_options['transactions'] !== FALSE;

    // MySQL never supports transactional DDL.
    $this->transactionalDDLSupport = FALSE;
    $this->connectionOptions = $connection_options;
    $charset = 'utf8';

    // Check if the charset is overridden to utf8mb4 in settings.php.
    if ($this
      ->utf8mb4IsActive()) {
      $charset = 'utf8mb4';

    // The DSN should use either a socket or a host/port.
    if (isset($connection_options['unix_socket'])) {
      $dsn = 'mysql:unix_socket=' . $connection_options['unix_socket'];
    else {

      // Default to TCP connection on port 3306.
      $dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . (empty($connection_options['port']) ? 3306 : $connection_options['port']);

    // Character set is added to dsn to ensure PDO uses the proper character
    // set when escaping. This has security implications. See
    // for further discussion.
    $dsn .= ';charset=' . $charset;
    $dsn .= ';dbname=' . $connection_options['database'];

    // Allow PDO options to be overridden.
    $connection_options += array(
      'pdo' => array(),
    $connection_options['pdo'] += array(
      // So we don't have to mess around with cursors and unbuffered queries by default.
      // Because MySQL's prepared statements skip the query cache, because it's dumb.
    if (defined('PDO::MYSQL_ATTR_MULTI_STATEMENTS')) {

      // An added connection option in PHP 5.5.21+ to optionally limit SQL to a
      // single statement like mysqli.
      $connection_options['pdo'] += array(
    parent::__construct($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);

    // Force MySQL to use the UTF-8 character set. Also set the collation, if a
    // certain one has been set; otherwise, MySQL defaults to 'utf8_general_ci'
    // for UTF-8.
    if (!empty($connection_options['collation'])) {
        ->exec('SET NAMES ' . $charset . ' COLLATE ' . $connection_options['collation']);
    else {
        ->exec('SET NAMES ' . $charset);

    // Set MySQL init_commands if not already defined.  Default Drupal's MySQL
    // behavior to conform more closely to SQL standards.  This allows Drupal
    // to run almost seamlessly on many different kinds of database systems.
    // These settings force MySQL to behave the same as postgresql, or sqlite
    // in regards to syntax interpretation and invalid data handling.  See
    // for further discussion. Also, as MySQL 5.5
    // changed the meaning of TRADITIONAL we need to spell out the modes one by
    // one.
    $connection_options += array(
      'init_commands' => array(),
    $connection_options['init_commands'] += array(

    // Execute initial commands.
    foreach ($connection_options['init_commands'] as $sql) {
  public function __destruct() {
    if ($this->needsCleanup) {
  public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
    return $this
      ->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);
  public function queryTemporary($query, array $args = array(), array $options = array()) {
    $tablename = $this
      ->query('CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY ' . $query, $args, $options);
    return $tablename;
  public function driver() {
    return 'mysql';
  public function databaseType() {
    return 'mysql';
  public function mapConditionOperator($operator) {

    // We don't want to override any of the defaults.
    return NULL;
  public function nextId($existing_id = 0) {
    $new_id = $this
      ->query('INSERT INTO {sequences} () VALUES ()', array(), array(
      'return' => Database::RETURN_INSERT_ID,

    // This should only happen after an import or similar event.
    if ($existing_id >= $new_id) {

      // If we INSERT a value manually into the sequences table, on the next
      // INSERT, MySQL will generate a larger value. However, there is no way
      // of knowing whether this value already exists in the table. MySQL
      // provides an INSERT IGNORE which would work, but that can mask problems
      // other than duplicate keys. Instead, we use INSERT ... ON DUPLICATE KEY
      // UPDATE in such a way that the UPDATE does not do anything. This way,
      // duplicate keys do not generate errors but everything else does.
        ->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(
        ':value' => $existing_id,
      $new_id = $this
        ->query('INSERT INTO {sequences} () VALUES ()', array(), array(
        'return' => Database::RETURN_INSERT_ID,
    $this->needsCleanup = TRUE;
    return $new_id;
  public function nextIdDelete() {

    // While we want to clean up the table to keep it up from occupying too
    // much storage and memory, we must keep the highest value in the table
    // because InnoDB  uses an in-memory auto-increment counter as long as the
    // server runs. When the server is stopped and restarted, InnoDB
    // reinitializes the counter for each table for the first INSERT to the
    // table based solely on values from the table so deleting all values would
    // be a problem in this case. Also, TRUNCATE resets the auto increment
    // counter.
    try {
      $max_id = $this
        ->query('SELECT MAX(value) FROM {sequences}')

      // We know we are using MySQL here, no need for the slower db_delete().
        ->query('DELETE FROM {sequences} WHERE value < :value', array(
        ':value' => $max_id,
    } catch (PDOException $e) {

   * Overridden to work around issues to MySQL not supporting transactional DDL.
  protected function popCommittableTransactions() {

    // Commit all the committable layers.
    foreach (array_reverse($this->transactionLayers) as $name => $active) {

      // Stop once we found an active transaction.
      if ($active) {

      // If there are no more layers left then we should commit.
      if (empty($this->transactionLayers)) {
        if (!PDO::commit()) {
          throw new DatabaseTransactionCommitFailedException();
      else {

        // Attempt to release this savepoint in the standard way.
        try {
            ->query('RELEASE SAVEPOINT ' . $name);
        } catch (PDOException $e) {

          // However, in MySQL (InnoDB), savepoints are automatically committed
          // when tables are altered or created (DDL transactions are not
          // supported). This can cause exceptions due to trying to release
          // savepoints which no longer exist.
          // To avoid exceptions when no actual error has occurred, we silently
          // succeed for MySQL error code 1305 ("SAVEPOINT does not exist").
          if ($e->errorInfo[1] == '1305') {

            // If one SAVEPOINT was released automatically, then all were.
            // Therefore, clean the transaction stack.
            $this->transactionLayers = array();

            // We also have to explain to PDO that the transaction stack has
            // been cleaned-up.
          else {
            throw $e;
  public function utf8mb4IsConfigurable() {
    return TRUE;
  public function utf8mb4IsActive() {
    return isset($this->connectionOptions['charset']) && $this->connectionOptions['charset'] === 'utf8mb4';
  public function utf8mb4IsSupported() {

    // Ensure that the MySQL driver supports utf8mb4 encoding.
    $version = $this
    if (strpos($version, 'mysqlnd') !== FALSE) {

      // The mysqlnd driver supports utf8mb4 starting at version 5.0.9.
      $version = preg_replace('/^\\D+([\\d.]+).*/', '$1', $version);
      if (version_compare($version, '5.0.9', '<')) {
        return FALSE;
    else {

      // The libmysqlclient driver supports utf8mb4 starting at version 5.5.3.
      if (version_compare($version, '5.5.3', '<')) {
        return FALSE;

    // Ensure that the MySQL server supports large prefixes and utf8mb4.
    try {
        ->query("CREATE TABLE {drupal_utf8mb4_test} (id VARCHAR(255), PRIMARY KEY(id(255))) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci ROW_FORMAT=DYNAMIC ENGINE=INNODB");
    } catch (Exception $e) {
      return FALSE;
      ->query("DROP TABLE {drupal_utf8mb4_test}");
    return TRUE;



Namesort descending Modifiers Type Description Overrides
DatabaseConnection::$connectionOptions protected property The connection information for this connection object.
DatabaseConnection::$driverClasses protected property Index of what driver-specific class to use for various operations.
DatabaseConnection::$escapedAliases protected property List of escaped aliases names, keyed by unescaped aliases.
DatabaseConnection::$escapedNames protected property List of escaped database, table, and field names, keyed by unescaped names.
DatabaseConnection::$key protected property The key representing this connection.
DatabaseConnection::$logger protected property The current database logging object for this connection.
DatabaseConnection::$prefixes protected property The prefixes used by this database connection.
DatabaseConnection::$prefixReplace protected property List of replacement values for use in prefixTables().
DatabaseConnection::$prefixSearch protected property List of search values for use in prefixTables().
DatabaseConnection::$schema protected property The schema object for this connection.
DatabaseConnection::$statementClass protected property The name of the Statement class for this connection.
DatabaseConnection::$target protected property The database target this connection is for.
DatabaseConnection::$temporaryNameIndex protected property An index used to generate unique temporary table names.
DatabaseConnection::$transactionalDDLSupport protected property Whether this database connection supports transactional DDL.
DatabaseConnection::$transactionLayers protected property Tracks the number of "layers" of transactions currently active.
DatabaseConnection::$transactionSupport protected property Whether this database connection supports transactions.
DatabaseConnection::commit public function Throws an exception to deny direct access to transaction commits.
DatabaseConnection::defaultOptions protected function Returns the default query options for any given query.
DatabaseConnection::delete public function Prepares and returns a DELETE query object.
DatabaseConnection::destroy public function Destroys this Connection object.
DatabaseConnection::escapeAlias public function Escapes an alias name string.
DatabaseConnection::escapeField public function Escapes a field name string.
DatabaseConnection::escapeLike public function Escapes characters that work as wildcard characters in a LIKE pattern.
DatabaseConnection::escapeTable public function Escapes a table name string.
DatabaseConnection::expandArguments protected function Expands out shorthand placeholders.
DatabaseConnection::filterComment protected function Sanitize a query comment string.
DatabaseConnection::generateTemporaryTableName protected function Generates a temporary table name.
DatabaseConnection::getConnectionOptions public function Returns the connection information for this connection object.
DatabaseConnection::getDriverClass public function Gets the driver-specific override class if any for the specified class.
DatabaseConnection::getKey public function Returns the key this connection is associated with.
DatabaseConnection::getLogger public function Gets the current logging object for this connection.
DatabaseConnection::getTarget public function Returns the target this connection is associated with.
DatabaseConnection::insert public function Prepares and returns an INSERT query object.
DatabaseConnection::inTransaction public function Determines if there is an active transaction open.
DatabaseConnection::makeComment public function Flatten an array of query comments into a single comment string.
DatabaseConnection::makeSequenceName public function Creates the appropriate sequence name for a given table and serial field.
DatabaseConnection::merge public function Prepares and returns a MERGE query object.
DatabaseConnection::popTransaction public function Decreases the depth of transaction nesting. 1
DatabaseConnection::prefixTables public function Appends a database prefix to all tables in a query.
DatabaseConnection::prepareQuery public function Prepares a query string and returns the prepared statement. 2
DatabaseConnection::pushTransaction public function Increases the depth of transaction nesting. 1
DatabaseConnection::query public function Executes a query string against the database. 1
DatabaseConnection::rollback public function Rolls back the transaction entirely or to a named savepoint. 1
DatabaseConnection::schema public function Returns a DatabaseSchema object for manipulating the schema.
DatabaseConnection::select public function Prepares and returns a SELECT query object.
DatabaseConnection::setKey public function Tells this connection object what its key is.
DatabaseConnection::setLogger public function Associates a logging object with this connection.
DatabaseConnection::setPrefix protected function Set the list of prefixes used by this database connection.
DatabaseConnection::setTarget public function Tells this connection object what its target value is.
DatabaseConnection::startTransaction public function Returns a new DatabaseTransaction object on this connection.
DatabaseConnection::supportsTransactionalDDL public function Determines if this driver supports transactional DDL.
DatabaseConnection::supportsTransactions public function Determines if this driver supports transactions.
DatabaseConnection::tablePrefix public function Find the prefix for a table.
DatabaseConnection::transactionDepth public function Determines current transaction depth.
DatabaseConnection::truncate public function Prepares and returns a TRUNCATE query object.
DatabaseConnection::update public function Prepares and returns an UPDATE query object.
DatabaseConnection::version public function Returns the version of the database server.
DatabaseConnection_mysql::$needsCleanup protected property Flag to indicate if the cleanup function in __destruct() should run.
DatabaseConnection_mysql::databaseType public function Returns the name of the PDO driver for this connection. Overrides DatabaseConnection::databaseType
DatabaseConnection_mysql::driver public function Returns the type of database driver. Overrides DatabaseConnection::driver
DatabaseConnection_mysql::mapConditionOperator public function Gets any special processing requirements for the condition operator. Overrides DatabaseConnection::mapConditionOperator
DatabaseConnection_mysql::nextId public function Retrieves an unique id from a given sequence. Overrides DatabaseConnection::nextId
DatabaseConnection_mysql::nextIdDelete public function
DatabaseConnection_mysql::popCommittableTransactions protected function Overridden to work around issues to MySQL not supporting transactional DDL. Overrides DatabaseConnection::popCommittableTransactions
DatabaseConnection_mysql::queryRange public function Runs a limited-range query on this database object. Overrides DatabaseConnection::queryRange
DatabaseConnection_mysql::queryTemporary public function Runs a SELECT query and stores its results in a temporary table. Overrides DatabaseConnection::queryTemporary
DatabaseConnection_mysql::utf8mb4IsActive public function Checks whether utf8mb4 support is currently active. Overrides DatabaseConnection::utf8mb4IsActive
DatabaseConnection_mysql::utf8mb4IsConfigurable public function Checks whether utf8mb4 support is configurable in settings.php. Overrides DatabaseConnection::utf8mb4IsConfigurable
DatabaseConnection_mysql::utf8mb4IsSupported public function Checks whether utf8mb4 support is available on the current database system. Overrides DatabaseConnection::utf8mb4IsSupported
DatabaseConnection_mysql::__construct public function Overrides DatabaseConnection::__construct
DatabaseConnection_mysql::__destruct public function