Update QueryBuilder.php

lib/Doctrine/DBAL/Query/QueryBuilder.php

@@ -1308,10 +1308,10 @@ class QueryBuilder
         $sql = '';
 
         if (isset($this->sqlParts['join'][$fromAlias])) {
+            foreach ($this->sqlParts['join'][$fromAlias] as $join) {
                 if (array_key_exists($join['joinAlias'], $knownAliases)) {
                     throw QueryException::notUniqueAlias($join['joinAlias'], $knownAliases);
                 }
-            foreach ($this->sqlParts['join'][$fromAlias] as $join) {
                 $sql .= ' ' . strtoupper($join['joinType'])
                     . ' JOIN ' . $join['joinTable'] . ' ' . $join['joinAlias']
                     . ' ON ' . ((string) $join['joinCondition']);