public function addPrimaryKey($name, $table, $columns)
    {
        $time = $this->beginCommand("add primary key $name on $table (" . (is_array($columns) ? implode(',', $columns) : $columns) . ')');
        $this->db->createCommand()->addPrimaryKey($name, $table, $columns)->execute();
        $this->endCommand($time);
    }