想用更新触发器更新多条记录

Question

让我解释一下我的场景。 假设我在“Activities”表中有10条记录，并带有“EstimatedDate”列。每个记录都是唯一的，并具有不同的“EstimatedDate”。这10条记录都属于同一个项目，具有相同的“ProjectId”。 如果我更改一行的“EstimatedDate”，它应该自动更改具有相同“ProjectId”的表中的以下行。

Answer 1

CREATE TRIGGER dbo.Activities_Update 
ON dbo.Activities 
AFTER UPDATE 
AS 
BEGIN 
    SET NOCOUNT ON; 
    UPDATE a 
    SET EstimatedDate = i.EstimatedDate 
    FROM dbo.Activities AS a 
    INNER JOIN inserted AS i 
    ON a.ProjectId = i.ProjectId 
    WHERE a.EstimatedDate <> i.EstimatedDate; 
END 
GO 

虽然这是不可能的，你UPDATE声明是这样的：

UPDATE Activities SET EstimatedDate = CASE 
    WHEN ActivityID = 1 THEN GETDATE() 
    WHEN ActivityID = 2 THEN DATEADD(DAY, 1, GETDATE()) END 
WHERE ProjectID = 1; 

如果你想要使用inserted的MAX日期，你可以说：

CREATE TRIGGER dbo.Activities_Update 
ON dbo.Activities 
AFTER UPDATE 
AS 
BEGIN 
    SET NOCOUNT ON; 

    ;WITH i AS (SELECT ProjectId, d = MAX(EstimatedDate) 
    FROM inserted GROUP BY ProjectId) 
    UPDATE a 
    SET EstimatedDate = i.d 
    FROM dbo.Activities AS a 
    INNER JOIN i 
    ON a.ProjectId = i.ProjectId 
    WHERE a.EstimatedDate <> i.d; 
END 
GO 

后者是未经测试。