Question

出于性能方面的考虑，我只需要删除循环并使用一些联接或其他解决方案来更新#Result表中的数据并获得相同的结果，即可循环返回。

标量函数：

CREATE FUNCTION [MultiplyerScl]
    (@a INT, @b INT)
RETURNS INT
AS
BEGIN
    DECLARE @i AS INT = 2
    DECLARE @Value AS INT 

    IF (@b % @a = 0) 
    BEGIN
        SET @Value = @b
    END
    ELSE 
    BEGIN
        WHILE (1=1) 
        BEGIN
            IF((@b * @i) % @a = 0) 
            BEGIN
                SET @Value = @b * @i
                BREAK;
            END
            ELSE 
            BEGIN
                SET @i = @i + 1
            END
        END
    END

    RETURN @Value
END

表设计及其价值。

CREATE TABLE #NUM (Groupid INT, GroupValue INT)

INSERT INTO #NUM 
VALUES (1, 8), (1, 9), (1, 23), (2, 5), (2, 5), (2, 10)

主要用于循环逻辑。

SELECT 
    Groupid,
    GroupValue,
    MaxValue = MAX(GroupValue) OVER (PARTITION BY Groupid),
    MaxCount = COUNT(1) OVER(),
    RID = ROW_NUMBER() OVER (ORDER BY groupid)
INTO 
    #Result
FROM 
    #NUM 

DECLARE @i AS INT = 1
DECLARE @RawCnt AS INT = (SELECT MAX(MaxCount) FROM #Result)
DECLARE @iGroupid INT
DECLARE @iGroupvalue INT
DECLARE @iMaxValue INT

WHILE(@i <= @RawCnt) 
BEGIN
    SELECT 
        @iGroupid = Groupid,
        @iGroupvalue = Groupvalue,
        @iMaxValue = MaxValue 
    FROM 
        #Result 
    WHERE 
        RID = @i

    UPDATE #Result
    SET MaxValue = dbo.[MultiplyerScl](@iGroupvalue, @iMaxValue)
    WHERE Groupid = @iGroupid

    SET @i = @i + 1
END

SELECT * FROM #Result

如何在SQL Server中更新没有循环的列？

0 个答案: