SQL删除触发器

Question

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，一旦我在 Table_1 中删除一行(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，会删除 Table_3 中的相应行。

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。

Answer 1

您的触发器将在稍作更正(删除拼写错误)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;

参见 sql fiddle demo