Question

我正在尝试使用DECIMAL（5,2）数据类型更新列。但是，SQL Server似乎是四舍五入而不是存储小数位。

例如，其中一个值为1.53，并在表中存储为1.00。

这是查询

DECLARE @MaxLike DECIMAL (5,2), @MaxComment DECIMAL (5,2), @MaxFavourite DECIMAL (5,2)
SET @MaxLike = 1.0*100/(SELECT MAX(z.MaxLike) FROM (SELECT(COUNT(COALESCE(Liked,0))) AS MaxLike FROM Design_LikeRating GROUP BY DesignID) z)
SET @MaxComment = 1.0*100/(SELECT MAX(z.MaxComment) FROM (SELECT(COUNT(COALESCE(CommentID,0))) AS MaxComment FROM Comment_CommentDetail WHERE IsDeleted = 0 GROUP BY OverallParentGUID) z)
SET @MaxFavourite = 1.0*100/(SELECT MAX(z.MaxFavourite) FROM (SELECT (COUNT(COALESCE(DesignID,0))) AS MaxFavourite FROM Design_Favourite GROUP BY DesignID) z)


-- VoteCount and Rate
DECLARE @table1 TABLE (DesignID INT PRIMARY KEY, Rate DECIMAL(5,2))
INSERT INTO @table1
SELECT DesignID, CAST (Rate AS DECIMAL(5,2)) AS Rate
FROM 
(
SELECT  DesignID, COUNT(COALESCE(Liked,0.0)) AS Rate
FROM Design_LikeRating WITH (NOLOCK)
GROUP BY DesignID
) z

-- FavCount
DECLARE @table2 TABLE (DesignID INT PRIMARY KEY, FavCount DECIMAL(5,2))
INSERT INTO @table2
SELECT DesignID, CAST (FavCount AS DECIMAL (5,2)) AS FavCount
FROM
(
SELECT DesignID, COUNT(COALESCE(DesignID,0.0)) AS FavCount 
FROM Design_Favourite WITH (NOLOCK)
GROUP BY DesignID
) x

-- CommentCount
DECLARE @table3 TABLE (DesignGUID UNIQUEIDENTIFIER PRIMARY KEY, CommentCount DECIMAL(5,2))
INSERT INTO @table3
SELECT OverallParentGUID, CAST (CommentCount AS DECIMAL(5,2)) AS CommentCount
FROM
(
SELECT OverallParentGUID, COUNT(DISTINCT COALESCE(x.DesignID,0.0)) AS CommentCount 
FROM Comment_CommentDetail z WITH (NOLOCK) 
    INNER JOIN Design_DesignDetail x WITH (NOLOCK) ON x.DesignGUID = z.OverallParentGUID
WHERE z.IsDeleted = 0 AND x.UserIDInt != z.UserIDInt
GROUP BY OverallParentGUID
) y
;

WITH CTE AS
            (
            SELECT (COALESCE((1.0 * z.Rate*@MaxLike),0.0) + COALESCE((1.0 * y.FavCount*@MaxFavourite),0.0) + COALESCE((1.0 * x.CommentCount*@MaxFavourite),0.0)) AS PopularityScore, a.DesignID
            FROM Design_DesignDetail a 
                LEFT JOIN @table1 AS z ON z.DesignID = a.DesignID 
                LEFT JOIN @table2 AS y ON y.DesignID = a.DesignID 
                LEFT JOIN @table3 AS x ON x.DesignGUID = a.DesignGUID 
            WHERE DesignID > 300000 and DesignID = 444409
            )

UPDATE  Design_DesignDetail
SET     PopularityScore =  z.PopularityScore
FROM    Design_DesignDetail a 
        INNER JOIN CTE z  on z.DesignID = a.DesignID

更新我会停止尝试聪明并在这里发布整个查询。正如你所看到的，它得到了一点点每个人的答案，但它仍然没有用！

Answer 1

此表达式必须为int或小数，其标度为0（无dec dec）

(ISNULL((z.Rate*@MaxLike),0) + ISNULL((y.FavCount*@MaxFavourite),0) + ISNULL((x.CommentCount*@MaxFavourite),0))

我猜你需要CAST才能在不知道数据类型的情况下在每个ISNULL中浮动

请不要像那样使用NOLOCK

完整代码更新后编辑

您的COUNT聚合将返回int值，因此您的小数（5,2）值可能包含xxx.00。

有些评论已添加到@ table1 loading

INSERT INTO @table1
SELECT DesignID,
-- gbn The CAST changes 2 to 2.00
CAST (Rate AS DECIMAL(5,2)) AS Rate
FROM 
(
SELECT  DesignID,
     -- gbn COALESCE does nothing. COUNT gives int and simply counts non-null values
     COUNT(COALESCE(Liked,0.0)) AS Rate 
FROM Design_LikeRating WITH (NOLOCK)
GROUP BY DesignID
) z

有关详细说明，请参阅我的答案Count(*) vs Count(1)

Answer 2

你可能会遇到整数数学的某些问题。

除非你喜欢舍入错误，否则在进行计算时永远不要使用浮点数。

Answer 3

z.Rate，@ MaxLike，y.FavCount，@ MaxFavourite和x.CommentCount有哪些类型？

我打赌y.FavCount和x.CommentCount是整数。

Answer 4

SELECT ISNULL(1.0 * z.Rate*@MaxLike, 0.0) +
       ISNULL(1.0 * y.FavCount*@MaxFavourite, 0.0) + 
       ISNULL(1.0 * x.CommentCount*@MaxFavourite, 0.0) AS PopularityScore, a.DesignID

SQL Server Update不更新小数

4 个答案: