Asp.net SQL中的嵌套触发器

我有以下表格：回复和消息。我想模仿Facebook的行为：当一条消息被删除时，所有相关的回复也会被删除。我的桌子是这样的：

REPLIES
messageId                               replyId
6b61d107-dff3-4374-a3a2-75ac7478a2f2    865c873d-0210-482a-b8bd-371c4f07f0cf

MESSAGES
id                                      body
865c873d-0210-482a-b8bd-371c4f07f0cf    this is the reply
6b61d107-dff3-4374-a3a2-75ac7478a2f2    this is the message

我已经创建了一个first触发器，它可以工作，当消息被删除时，它会删除回复中的相关行。现在，我想创建另一个触发器，它将在每次删除回复中的一行时删除相关消息。现在回复变成了他们自己的信息，这是没有意义的。这是第二个触发点：

CREATE TRIGGER TRG_DEL_MESSAGES
ON Replies
FOR DELETE
AS
DELETE FROM Messages WHERE id = (SELECT replyId FROM DELETED)

当我尝试删除某些内容时，会出现以下错误：

Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).

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显然有一个无限循环在进行，我认为这是因为删除的表由第一个触发器的数据填充，而第一个触发器触发了第二个触发器。但我真的不确定，我很感谢你的帮助。谢谢

像这样的东西对你有用吗？只需在消息上使用一个触发器就可以删除递归，该触发器会预先计算所有相关消息，所以您最多应该得到一个嵌套调用？它从消息和回复中删除所有相关消息

CREATE TRIGGER TRG_DEL_REPLIES
ON [Messages]
FOR DELETE
AS
BEGIN
    DECLARE @Related TABLE (MessageId uniqueidentifier)

    --get all related messages so that we don't recurse
    BEGIN
        WITH AllReplies (MessageId)
        AS
        (
            --Anchor
            SELECT  D.MessageId
            FROM    Deleted D
            UNION ALL
            --Recurse
            SELECT  R.ReplyId
            FROM    AllReplies AR
            JOIN    Replies R
                    ON AR.MessageId = R.MessageId
        )
        INSERT  INTO @Related
        SELECT  * 
        FROM    AllReplies
    END

    --delete the replies

    DELETE  R
    FROM    Replies R
    JOIN    @Related REL
            ON R.MessageId = REL.MessageId

    --delete the messages

    DELETE  M
    FROM    [Messages] M
    JOIN    @Related REL
            ON  REL.MessageId = M.MessageId 
    LEFT
    JOIN    DELETED D
            ON REL.MessageId = D.MessageId
    WHERE   D.MessageId IS NULL
END

要将其转换为您想要的存储过程，我将这样做，而不是执行多个单独删除的循环：

CREATE PROCEDURE DeleteMessageWithReplies(@messageId uniqueidentifier)
AS
BEGIN
    DECLARE @Related TABLE (MessageId uniqueidentifier)

    --get all related messages
    BEGIN
        WITH AllReplies (MessageId)
        AS
        (
            --Anchor
            SELECT  @messageId
            UNION ALL
            --Recurse
            SELECT  R.ReplyId
            FROM    AllReplies AR
            JOIN    Replies R
                    ON AR.MessageId = R.MessageId
        )
        INSERT  INTO @Related
        SELECT  * 
        FROM    AllReplies
    END

    --delete the replies

    DELETE  R
    FROM    Replies R
    JOIN    @Related REL
            ON R.MessageId = REL.MessageId

    --delete the messages that haven't already been deleted

    DELETE  M
    FROM    [Messages] M
    JOIN    @Related REL
            ON  REL.MessageId = M.MessageId 
END

---

谢谢你的帮助，弗格斯，我很感激。然而，正如@Ben所指出的，存储过程更容易编写，也更简单。这就是我刚刚写的，它可能会得到改进，但至少它是有效的

EXEC('CREATE PROCEDURE deleteMessageWithReplies(@messageId uniqueidentifier)
AS
BEGIN
    DECLARE @repliesCount int
    SELECT @repliesCount = (SELECT COUNT(*) FROM Replies WHERE messageId=@messageId)
    DECLARE @cpt int
SET @cpt = 0
DELETE FROM Messages WHERE id = @messageId
WHILE @cpt < @repliesCount
BEGIN
    DECLARE @replyId uniqueidentifier
    SELECT @replyId = (SELECT TOP 1 replyId FROM Replies WHERE messageId=@messageId)
    DELETE FROM Replies WHERE replyId = @replyId
    DELETE FROM Messages WHERE id=@replyId
    SET @cpt = @cpt+1
END
END')

---

我建议要么像Fergus Bown建议的那样在触发器中一次生成所有删除，要么将删除逻辑移动到存储过程调用。在我们的应用程序中，所有CRUD操作都使用存储过程方法创建、读取、更新和删除

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缺点是，如果新手支持DBA使用SQL删除单个回复而不删除与之相关的所有其他消息，那么他们可能会出错。但是这样的DBA应该知道如何使用存储过程，或者首先正确使用SQL。

VisualStudio2010中的SQL Express。简单的答案是不要使用嵌套触发器。。。它们导致了你所看到的问题。如果改用存储过程，您的生活会更轻松，代码也不会那么混乱，因为它们都在一个地方。另一个建议。。。为什么不使用级联删除？@Boomer:cascade deletes是我第一次尝试，但我也遇到了同样的问题。在尝试级联删除之前，你是否禁用了触发器？