Question

在SQL Server数据库中有两个表。表＃1 ClassicsRatings以RatingID为关键，TitleID，Rating和Comment。表＃2，AVGRating，TitleID为关键，AvgRating和Count。

以下查询在表＃1上最初运行查询时更新表＃2：

INSERT INTO AVGRating
   SELECT TitleID, Count(*) AS Count, AVG(Rating) AS AvgRating
   FROM ClassicsRatings
   GROUP BY TitleID
   ORDER BY TitleID

我的问题是：当后续的INSERTS进入表＃1时，如何让表＃2更新。我尝试了MERGE和UPDATE，如下所示：

MERGE AVGRating AS AR
USING ( SELECT TitleID, COUNT(*) AS Count, AVG(Rating) AS AvgRating
FROM ClassicsRatings
GROUP BY RecipeID) AS ClassicsRatings(RecipeID, Count, AvgRating)
ON
(
AR.RecipeID = ClassicsRatings.RecipeID
)
WHEN NOT MATCHED THEN
   INSERT (RecipeID, Count, AvgRating)
   VALUES (ClassicsRatings.RecipeID, ClassicsRatings.Count, ClassicsRatings.AvgRating)
WHEN MATCHED THEN
   UPDATE
    SET AR.Count = ClassicsRatings.Count, 
        AR.AvgARating = ClassicsRatings.AvgRating;

UPDATE AVGRating
SET
AVGRating.TitleID = ClassicsRatings.TitleID,
AVGRating.AvgRating = ClassicsRatings.AvgRating,
AVGRating.Count = ClassicsRatings.Count
FROM AVGRating
INNER JOIN ClassicsRatings ON
AVGRating.TitleID = ClassicsRatings.TitleID
WHERE TitleID = TitleID

我不能做的是插入表1并让表2反映INSERT。任何帮助将不胜感激。

我还使用了以下TRIGGER而没有结果：

CREATE TRIGGER AVGRatingTrigger
ON ClassicsRatings
AFTER INSERT AS
DECLARE @TitleID INT
DECLARE @Count INT
DECLARE @RatingAVG INT
BEGIN
UPDATE AVGRatings
WHERE AVGRatings.TitleID = ClassicsRatings.TitleID 
END

触发器已更改为：

CREATE TRIGGER AVGRatingTrigger
ON ClassicsRatings
AFTER INSERT AS

BEGIN
UPDATE A
SET A.TitleID = I.TitleID,
A.Count = I.Count,
A.AvgRating = I.AvgRating
FROM AVGRating as A
INNER JOIN INSERTED as I ON A.TitelID = I.TitleID 
END

我没有触发器的错误消息，但是，当我将新的评级插入ClassicRatings时，我收到错误消息“Invalid object AvgRating”AVG（等级）AS AvgRating的AvgRating部分似乎在AVGRating表中触发器未识别（初始查询确实识别AvgRating）。我认为这意味着，因为ClassicsRatings实际上没有AvgRating，但会进行计算/聚合并使用计算填充AVGRating表，从而发生冲突。我已经试了两天才能让它发挥作用。我的问题似乎出现在A.Count = I.Count A.AvgRating = I.AvgRating中，因为ClassicsRatings表中的Count实际上是COUNT（*） - 不是ClassicsRatings中的字段而AvgRating实际上是AVG（评级） - 不是ClassicsRatings中的一个字段。任何帮助将不胜感激。

Answer 1

您需要使用触发器来实现这一目标。只需创建一个“on insert”触发器，当有第一个表的插入时，它会运行查询。

在触发器中，您应该使用逻辑INSERTED，其中包含插入的行。类似的东西：

CREATE TRIGGER AVGRatingTrigger
ON ClassicsRatings
AFTER INSERT AS

BEGIN
UPDATE A
SET A.xxx = I.xxx,
    A.yyy = I.yyy,
    ...
FROM AVGRatings as A
INNER JOIN INSERTED as I ON A.TitleID = I.TitleID 
END

SQL Server Table1 UPDATE Table2

1 个答案: