Model\Card::destroy PHP Method

    public function destroy()
    {
        $inTransaction = DB::getInstance()->inTransaction();
        if (!$inTransaction) {
            DB::getInstance()->beginTransaction();
        }
        $st = DB::sql("UPDATE card SET status=0 WHERE card=:card");
        // 失效卡
        $st->bindValue(":card", $this->card, DB::PARAM_STR);
        $flag = $st->execute();
        if (!$inTransaction) {
            DB::getInstance()->commit();
        }
        return $flag;
    }