Question

下面的更新声明按预期工作。但是，我需要将语句循环50次。我尝试编写一个循环，允许我更改从Seg1到SegX设置的字段，并更新SubString（GoalBusinessSegment，（6 * 1）-5,5）AS＆＃39; Seg＆＃39;到SubString（GoalBusinessSegment，（6 * X）-5,5）AS＆＃39; Seg＆＃39;

UPDATE [dbo].[MULTBUSSEGTEST]
SET Seg1 = SegTBL.Seg
FROM (SELECT DISTINCT GoalBusinessSegment,SubString(GoalBusinessSegment,(6*1)-5,5) AS 'Seg'
      FROM [2017].[dbo].[WPGDM]
      WHERE GoalID BETWEEN 22.1 AND 22.4 AND 
            LEFT(GoalBusinessSegment,1) = 'B' AND LEN(GoalBusinessSegment) > 5
     ) SegTBL
WHERE [dbo].[MULTBUSSEGTEST].SegID = SegTBL.GoalBusinessSegment

以下是我在循环中的尝试。

DECLARE @LoopCount int
DECLARE @SegField varchar(255)
DECLARE @i int

DELETE FROM [dbo].[MULTBUSSEGTEST]

INSERT INTO     [dbo].[MULTBUSSEGTEST]
SELECT DISTINCT GoalBusinessSegment AS 'SegID'
            ,NULL AS 'Seg1'
            ,NULL AS 'Seg2'
            ,NULL AS 'Tgt1'
            ,NULL AS 'Tgt2'
            ,NULL AS 'Act1'
            ,NULL AS 'Act2'
FROM        [2017].[dbo].[WPGDM]
WHERE       GoalID BETWEEN 22.1 AND 22.4 AND LEFT(GoalBusinessSegment,1) = 'B' AND LEN(GoalBusinessSegment) > 5

Set @LoopCount = (SELECT FLOOR(MAX(LEN(GoalBusinessSegment))/5)
                  FROM [2017].[dbo].[WPGDM]
                 )
WHILE @i <= @LoopCount 
BEGIN
Set @SegField = 'Seg' + @LoopCount
UPDATE [dbo].[MULTBUSSEGTEST]
  SET @SegField = SegTBL.Seg
  FROM (SELECT DISTINCT GoalBusinessSegment
            ,SubString(GoalBusinessSegment,(6*@i)-5,5) AS 'Seg'
            FROM [2017].[dbo].[WPGDM]
            WHERE GoalID BETWEEN 22.1 AND 22.4 AND LEFT(GoalBusinessSegment,1) = 'B' AND LEN(GoalBusinessSegment) > 5
       ) SegTBL
 WHERE [dbo].[MULTBUSSEGTEST].SegID = SegTBL.GoalBusinessSegment
 SET @i = @i + 1
END

循环产生所有空值，我缺少什么？

Answer 1

意识到不需要多个字段和更新语句。问题解决了。

如何使用动态列名更新表？

1 个答案: