UPDATE上的MSSQL触发器:支持多行更新

Question

我有一个SQL触发器，它在表更新时触发。当表被更新时，它会修改另一个表中的一些字段。

它似乎正在工作，但我不确定我设置状态的方式是否正确(如果插入包含多行)。我测试了一下，得到了正确的答案(但我仍然怀疑这不是正确的/最好的方法)。

CREATE TRIGGER [dbo].[myTrigger]
ON [dbo].[myTable]
AFTER UPDATE
AS
BEGIN
    SET NOCOUNT ON
    declare @OldStatus int
    declare @NewStatus int
    select @OldStatus = [currentStatus] FROM INSERTED 
    if @OldStatus = 1 or @OldStatus = 3 or @OldStatus = 5
    begin
        set @NewStatus = 1
    end 
    if @OldStatus = 8 or @OldStatus = 9
    begin
        set @NewStatus = 8
    end
    if @OldStatus = 11 or @OldStatus = 12 or @OldStatus = 13
    begin
        set @NewStatus = 11
    end
    UPDATE myNewTable SET        [LastModifiedDate] = GETDATE(),
                                 [Status] = @NewStatus,
                                 [Type] = inserted.Type
    FROM inserted
    WHERE ([id] = inserted.id)
END

我认为正确的解决方案应该是这样的:

UPDATE myNewTable SET        [LastModifiedDate] = GETDATE(),
                             [Status] = ***<add logic here>***,
                             [Type] = inserted.Type
FROM inserted
WHERE ([id] = inserted.id)

Answer 1

你需要这样做:

CREATE TRIGGER [dbo].[myTrigger]
    ON [dbo].[myTable]
    AFTER UPDATE
AS
BEGIN
    SET NOCOUNT ON;
    UPDATE 
        myNewTable 
    SET
        LastModifiedDate=GETDATE(),
        Status= 
            CASE 
                WHEN i.currentStatus IN (1,3,5) THEN 1
                WHEN i.currentStatus IN (8,9) THEN 8
                WHEN i.currentStatus IN (11,12,13) THEN 11
                ELSE NULL -- if the current status isn't in the cases above
            END,
        Type=i.Type
    FROM 
        myNewTable AS mnt
        INNER JOIN inserted AS i ON
            i.id=mnt.id;
END