Doctrine/DBAL/Driver/PDODblib/Driver.php
public function connect(array $params, $username = null, $password = null, array $driverOptions = [])
    {
        if (PlatformHelper::isWindows()) {
            return $this->connectWindows($params, $username, $password, $driverOptions);
        }
        return $this->connectUnix($params, $username, $password, $driverOptions);
    }
public function connect(array $params, $username = null, $password = null, array $driverOptions = [])
    {
        if (PlatformHelper::isWindows()) {
            return $this->connectWindows($params, $username, $password, $driverOptions);
        }
        return $this->connectUnix($params, $username, $password, $driverOptions);
    }
Attempts to establish a connection with the underlying driver.

@param array $params
@param string $username
@param string $password
@param array $driverOptions
@return \Doctrine\DBAL\Driver\Connection