Both databases have dialect 1 and that means that case in table names and quotation is irrelevant. I managed to call generator from 1.5 database but tables are not accessible still from the Active record infrastrcture:
$list = Yii::$app->db->createCommand('select gen_id(contract_ino, 1) from rdb$database')->queryAll(); var_dump($list); I guess that raw queries can be executed succesfully for both databases. Jonatan