PDO使用FOR UPDATE更新错误的序列

Question

我有一个简单的脚本，我希望在使用以下代码更新'Lookup'表（增加'nDeger'行）后更新表'Isler'：

        $PDOvt = new PDO ('mysql:dbname=' . VTAD . ';host=localhost', VTKA, VTP);
        $PDOvt->setAttribute (PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        try
        {
            $Q2 = "SELECT @GRUPID:=nDeger as grupId FROM Lookup WHERE cAlan = 'nGrupId' FOR UPDATE;";
            $Q3 = "UPDATE Lookup SET nDeger = nDeger + 1 WHERE cAlan = 'nGrupId';";
            $Q4 = "UPDATE Isler SET nGrupId = @GRUPID
        WHERE 
            konukID = :oturumKaydi
        AND 
            kID = :kid
        AND 
            nSiparisDurum = '-1' 
        AND 
            (durum = 4 OR durum = 5);";

            $PDOvt->beginTransaction ();

            $SMTP2 = $PDOvt->prepare ($Q2);

            $SMTP3 = $PDOvt->prepare ($Q3);

            $SMTP4 = $PDOvt->prepare ($Q4);

            $SMTP4->bindValue (':oturumKaydi', $this->oturum_kaydi, PDO::PARAM_STR);
            $SMTP4->bindValue (':kid', $this->kullanici_id, PDO::PARAM_INT);


            $SMTP2->execute ();
            $SMTP3->execute ();
            $SMTP4->execute ();

            $PDOvt->commit ();

            $GRUPID = $SMTP2->fetchAll (PDO::FETCH_CLASS);
            $_SESSION['iliskili_grup'] = $GRUPID[0]->grupId;
            $this->iliskili_grup = $GRUPID[0]->grupId; // not incremented value



            $PDOvt = null;
            $this->debuggrupid = $vt->get_var("SELECT nDeger FROM Lookup WHERE cAlan = 'nGrupId' FOR UPDATE;"); // incremented value;

        } catch (PDOException $e)
        {
            $PDOvt->rollBack ();
            echo "HATA!";
        }

我添加了一个带有不同连接的最后一个查询来检查nDeger的最后一个值，它看起来是增量的。

但似乎mysql在增加Lookup之前更新'Isler'。我试图改变两个更新的位置，但没有任何改变。