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DatabaseConnection::$connectionOptionsThe connection information for this connection object.
DatabaseConnection::$driverClassesIndex of what driver-specific class to use for various operations.
DatabaseConnection::$keyThe key representing this connection.
DatabaseConnection::$loggerThe current database logging object for this connection.
DatabaseConnection::$prefixesThe prefixes used by this database connection.
DatabaseConnection::$prefixReplaceList of replacement values for use in prefixTables().
DatabaseConnection::$prefixSearchList of search values for use in prefixTables().
DatabaseConnection::$statementClassThe name of the Statement class for this connection.
DatabaseConnection::$targetThe database target this connection is for.
DatabaseConnection::$temporaryNameIndexAn index used to generate unique temporary table names.
DatabaseConnection::$transactionalDDLSupportWhether this database connection supports transactional DDL.
DatabaseConnection::$transactionLayersTracks the number of "layers" of transactions currently active.
DatabaseConnection::$transactionSupportWhether this database connection supports transactions.
DatabaseConnection_mysql::$shutdownRegisteredFlag to indicate if we have registered the nextID cleanup function.

Functions & methods

DatabaseConnection::commitThrows an exception to deny direct access to transaction commits.
DatabaseConnection::defaultOptionsReturns the default query options for any given query.
DatabaseConnection::deletePrepares and returns a DELETE query object.
DatabaseConnection::escapeAliasEscapes an alias name string.
DatabaseConnection::escapeFieldEscapes a field name string.
DatabaseConnection::escapeLikeEscapes characters that work as wildcard characters in a LIKE pattern.
DatabaseConnection::escapeTableEscapes a table name string.
DatabaseConnection::expandArgumentsExpands out shorthand placeholders.
DatabaseConnection::filterCommentSanitize a query comment string.
DatabaseConnection::generateTemporaryTableNameGenerates a temporary table name.
DatabaseConnection::getConnectionOptionsReturns the connection information for this connection object.
DatabaseConnection::getDriverClassGets the driver-specific override class if any for the specified class.
DatabaseConnection::getKeyReturns the key this connection is associated with.
DatabaseConnection::getLoggerGets the current logging object for this connection.
DatabaseConnection::getTargetReturns the target this connection is associated with.
DatabaseConnection::insertPrepares and returns an INSERT query object.
DatabaseConnection::inTransactionDetermines if there is an active transaction open.
DatabaseConnection::makeCommentFlatten an array of query comments into a single comment string.
DatabaseConnection::makeSequenceNameCreates the appropriate sequence name for a given table and serial field.
DatabaseConnection::mergePrepares and returns a MERGE query object.
DatabaseConnection::popTransactionDecreases the depth of transaction nesting.
DatabaseConnection::prefixTablesAppends a database prefix to all tables in a query.
DatabaseConnection::prepareQueryPrepares a query string and returns the prepared statement.
DatabaseConnection::pushTransactionIncreases the depth of transaction nesting.
DatabaseConnection::queryExecutes a query string against the database.
DatabaseConnection::rollbackRolls back the transaction entirely or to a named savepoint.
DatabaseConnection::schemaReturns a DatabaseSchema object for manipulating the schema.
DatabaseConnection::selectPrepares and returns a SELECT query object.
DatabaseConnection::setKeyTells this connection object what its key is.
DatabaseConnection::setLoggerAssociates a logging object with this connection.
DatabaseConnection::setPrefixSet the list of prefixes used by this database connection.
DatabaseConnection::setTargetTells this connection object what its target value is.
DatabaseConnection::startTransactionReturns a new DatabaseTransaction object on this connection.
DatabaseConnection::supportsTransactionalDDLDetermines if this driver supports transactional DDL.
DatabaseConnection::supportsTransactionsDetermines if this driver supports transactions.
DatabaseConnection::tablePrefixFind the prefix for a table.
DatabaseConnection::transactionDepthDetermines current transaction depth.
DatabaseConnection::truncatePrepares and returns a TRUNCATE query object.
DatabaseConnection::updatePrepares and returns an UPDATE query object.
DatabaseConnection::versionReturns the version of the database server.
DatabaseConnection_mysql::databaseTypeReturns the name of the PDO driver for this connection. Overrides DatabaseConnection::databaseType
DatabaseConnection_mysql::driverReturns the type of database driver. Overrides DatabaseConnection::driver
DatabaseConnection_mysql::mapConditionOperatorGets any special processing requirements for the condition operator. Overrides DatabaseConnection::mapConditionOperator
DatabaseConnection_mysql::nextIdRetrieves an unique id from a given sequence. Overrides DatabaseConnection::nextId
DatabaseConnection_mysql::popCommittableTransactionsOverridden to work around issues to MySQL not supporting transactional DDL. Overrides DatabaseConnection::popCommittableTransactions
DatabaseConnection_mysql::queryRangeRuns a limited-range query on this database object. Overrides DatabaseConnection::queryRange
DatabaseConnection_mysql::queryTemporaryRuns a SELECT query and stores its results in a temporary table. Overrides DatabaseConnection::queryTemporary
DatabaseConnection_mysql::__construct Overrides DatabaseConnection::__construct

includes/database/mysql/, line 13

View source
class DatabaseConnection_mysql extends DatabaseConnection {

   * Flag to indicate if we have registered the nextID cleanup function.
   * @var boolean
  protected $shutdownRegistered = 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;

    // 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']);
    $dsn .= ';dbname=' . $connection_options['database'];
    parent::__construct($dsn, $connection_options['username'], $connection_options['password'], 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. 
      // Force column names to lower case. 

    // 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'])) {
      $this->exec('SET NAMES utf8 COLLATE ' . $connection_options['collation']);
    else {
      $this->exec('SET NAMES utf8');

    // Force MySQL's 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.

  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->generateTemporaryTableName();
    $this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY SELECT', $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.
      $this->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(':value' => $existing_id));
      $new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
    if (!$this->shutdownRegistered) {
      // Use register_shutdown_function() here to keep the database system
      // independent of Drupal.
      register_shutdown_function(array($this, 'nextIdDelete'));
      $shutdownRegistered = 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}')->fetchField();
      // We know we are using MySQL here, no need for the slower db_delete().
      $this->query('DELETE FROM {sequences} WHERE value < :value', array(':value' => $max_id));
    // During testing, this function is called from shutdown with the
    // simpletest prefix stored in $this->connection, and those tables are gone
    // by the time shutdown is called so we need to ignore the database
    // errors. There is no problem with completely ignoring errors here: if
    // these queries fail, the sequence will work just fine, just use a bit
    // more database storage and memory.
    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 {
          $this->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, we keep just the topmost transaction.
            $this->transactionLayers = array('drupal_transaction' => 'drupal_transaction');
          else {
            throw $e;

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