public function DatabaseConnection_mysql::__construct

Constructs a MySQL-based DatabaseConnection.

Overrides DatabaseConnection::__construct

File

core/includes/database/mysql/database.inc, line 33

Database interface code for MySQL database servers.

Class

DatabaseConnection_mysql

MySQL database connection driver.

Code

public function __construct(array $connection_options = array()) {
  // Default to transaction support, unless explicitly set 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
  // https://www.drupal.org/node/1201452 for further discussion.
  $dsn .= ';charset=' . $charset;
  if (!empty($connection_options['database'])) {
    $dsn .= ';dbname=' . $connection_options['database'];
  }
  // Allow PDO options to be overridden.
  $connection_options += array(
    'pdo' => array(),
  );
  $connection_options['pdo'] += array(
    // Make sure MySQL returns all matched rows on update queries including
    // rows that actually didn't have to be updated because the values didn't
    // change. This matches common behaviour among other database systems.
    PDO::MYSQL_ATTR_FOUND_ROWS => TRUE,
    // Avoid mess around with cursors and unbuffered queries by default.
    PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
    // MySQL prepared statements skip the query cache, because it's dumb.
    PDO::ATTR_EMULATE_PREPARES => TRUE,
    // Convert numeric values to strings when fetching. In PHP 8.1,
    // PDO::ATTR_EMULATE_PREPARES now behaves the same way as non emulated
    // prepares and returns integers. See https://externals.io/message/113294
    // for further discussion.
    PDO::ATTR_STRINGIFY_FETCHES => TRUE,
    // Limit SQL to a single statement like mysqli.
    PDO::MYSQL_ATTR_MULTI_STATEMENTS => FALSE,
  );

  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'])) {
    $this->pdo->exec('SET NAMES ' . $charset . ' COLLATE ' . $connection_options['collation']);
  }
  else {
    $this->pdo->exec('SET NAMES ' . $charset);
  }

  // Set MySQL init_commands if not already defined.  Default Backdrop's MySQL
  // behavior to conform more closely to SQL standards.  This allows Backdrop
  // to run almost seamlessly on many different kinds of database systems.
  // 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(),
  );
  $connection_options['init_commands'] += array(
    'sql_mode' => "SET sql_mode = 'REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO'",
  );
  // Execute initial commands.
  foreach ($connection_options['init_commands'] as $sql) {
    $this->pdo->exec($sql);
  }
}