Merge pull request #5 from ovos/hotfix/mysql8-reserved-row_number-keyword

quote "row_number" keyword (reserved in MySQL 8)

Author: falkenhawk

lib/Doctrine/Query.php

@@ -1804,7 +1804,7 @@ public function getLimitSubquery()
                 // otherwise limit would be executed after ids are reordered by distinct / group by, and that order cannot be determined.
                 if ($driverName == 'mysql') {
                     // assign an incremented number to each row with id
-                    $subquery = 'SELECT @rownum:=@rownum + 1 as row_number,'
+                    $subquery = 'SELECT @rownum:=@rownum + 1 as ' . $this->_conn->quoteIdentifier('row_number') . ','
                         . ' doctrine_subquery_rownum_alias.' . $quotedIdentifierColumnName
                         . ' FROM (' . $subquery . ') doctrine_subquery_rownum_alias,'
                         . ' (SELECT @rownum := 0) rownum_var';