fixed conditional expression

lib/Doctrine/DBAL/Driver/PDOStatement.php

@@ -37,7 +37,7 @@ class PDOStatement extends \PDOStatement implements Statement
         // of PDOStatement::setFetchMode(): even if the second and third
         // parameters are optional, PHP will not let us remove it from this
         // declaration.
-        if ($arg2 === null || $arg3 === null) {
+        if ($arg2 === null && $arg3 === null) {
             return parent::setFetchMode($fetchStyle);
         }