Stop PHP foreach loop after start

Question

How to interrupt a foreach PHP based on a condition coming from the database after starting the loop?

        $smtm = Connect::getInstance()->query("SELECT * FROM table WHERE num IS NULL");
        foreach ($smtm->fetchAll() as $value) {
            //aqui vai o comando a ser executado.
            if (Connect::getInstance()->query("SELECT * FROM table WHERE num IS NULL")) {
                //encerra o loop se não encontrar NULL
                break;
            }
        }

Since the BD can be changed at runtime, I would like to break if the seat query meets the condition during the loop.