public function __construct($dsn = '', $username = '', $password = '')
{
parent::__construct($dsn, $username, $password);
$this->driverMap = array_merge($this->driverMap, array('mysql' => 'MysqlSchema', 'mysqli' => 'MysqlSchema', 'mssql' => 'MssqlSchema', 'dblib' => 'MssqlSchema', 'sqlsrv' => 'MssqlSchema', 'pgsql' => 'PgsqlSchema'));
}
