Doctrine\DBAL\Platforms\SQLServerPlatform::getSubstringExpression PHP Method

    public function getSubstringExpression($value, $from, $length = null)
    {
        if (!is_null($length)) {
            return 'SUBSTRING(' . $value . ', ' . $from . ', ' . $length . ')';
        }
        return 'SUBSTRING(' . $value . ', ' . $from . ', LEN(' . $value . ') - ' . $from . ' + 1)';
    }