SQL删除触发器在答案

【问题标题】：SQL delete trigger inSQL删除触发器在
【发布时间】：2013-09-08 11:12:05
【问题描述】：

假设我有三个表：

表_1：

 ID     INT     PRIMARY
 name NVARCHAR

表_2：

ID         INT    PRIMARY
Table_1_ID INT (foreign key)

表_3：

ID         INT    PRIMARY
Table_2_ID INT (foreign key)

前两个表有以下触发器：

-- Table_1
CREATE TRIGGER tr_1
ON Table_1
INSTEAD OF DELETE
AS
BEGIN
    DELETE FROM Table_2
    WHERE Table_1_ID IN (SELECT deleted.ID FROM Table_1)

    DELETE FROM Table_1
    WHERE ID IN (SELECT deleted.ID FROM deleted)
END

-- Table_2
CREATE TRIGGER sr_bf_trigger_delete_ID
ON Table_2
INSTEAD OF DELETE
AS
BEGIN
    DELETE FROM Table_3
    WHERE Table_2_ID IN (SELECT deleted.ID FROM deleted)

    DELETE FROM Table_2
    WHERE ID IN (SELECT deleted.ID FROM deleted)
END

这个想法是，一旦我删除Table_1 中的一行（或多行），它将启动触发器并删除Table_2 中的相应行。但是，在删除Table_2中的行之前，Table_3中的对应行被删除了。

这行得通吗？我看到的可能问题是我两次访问同一个“已删除”表。

【问题讨论】：

标签： sql sql-server triggers

【解决方案1】：

您的触发器将在稍作修正（删除错别字）后正常工作：

CREATE TRIGGER tr_1
ON Table_1
INSTEAD OF DELETE
AS
BEGIN
    DELETE FROM Table_2
    WHERE Table_1_ID IN (SELECT d.ID FROM deleted as d)

    DELETE FROM Table_1
    WHERE ID IN (SELECT d.ID FROM deleted as d)
END;

-- Table_2
CREATE TRIGGER sr_bf_trigger_delete_ID
ON Table_2
INSTEAD OF DELETE
AS
BEGIN
    DELETE FROM Table_3
    WHERE Table_2_ID IN (SELECT d.ID FROM deleted as d)

    DELETE FROM Table_2
    WHERE ID IN (SELECT d.ID FROM deleted as d)
END;

见sql fiddle demo

【讨论】：