There are issue with the mysqli driver and that method that silence t…

…he erros

It also prevented users to use the results of the sql calls made

lib/Doctrine/DBAL/Migrations/Version.php

@@ -379,7 +379,7 @@ private function executeRegisteredSql($dryRun = false, $timeAllQueries = false)
 
                     if ( ! isset($this->params[$key])) {
                         $this->outputWriter->write('     <comment>-></comment> ' . $query);
-                        $this->connection->exec($query);
+                        $this->connection->executeQuery($query);
                     } else {
                         $this->outputWriter->write(sprintf('    <comment>-</comment> %s (with parameters)', $query));
                         $this->connection->executeQuery($query, $this->params[$key], $this->types[$key]);