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T-SQL行合并成列与列拆分成行

2024-09-26 06:48:38   218人阅读

 

本文出处：http://www.cnblogs.com/wy123/p/6910468.html 

 

 

　　感觉最近sql也没少写，突然有一点生疏了，对于用的不是太频繁的一些操作，时间一久就容易生。

 

多行的某一个列合并成一个列

CREATE TABLE TestColumnMergeAndSplit(    Id int Identity(1,1),    BusinessId int,    BusinessValue varchar(20))GOINSERT INTO TestColumnMergeAndSplitSELECT 1,‘AAA‘UNION ALLSELECT 1,‘BBB‘UNION ALLSELECT 1,‘CCC‘UNION ALLSELECT 2,‘XXX‘UNION ALLSELECT 2,‘YYY‘UNION ALLSELECT 2,‘ZZZ‘GOSELECT * FROM TestColumnMergeAndSplitGOSELECT  t1.BusinessId,       STUFF       (            ( SELECT     ‘,‘+t2.BusinessValue               FROM      TestColumnMergeAndSplit t2              WHERE     t2.BusinessId = t1.BusinessId            FOR              XML PATH(‘‘)            ),            1,1,‘‘        )         AS ColNamesFROM   TestColumnMergeAndSplit t1GROUP BY t1.BusinessIdGO

技术分享

　　另外是一个相反的操作，借助上面合并之后的结果，将一个多个值的字符串列拆分开来，转换为多行，

　　技术分享

　　用到的字符串拆分函数，比较常见

CREATE FUNCTION [dbo].[fn_SplitStringToTable] (    @s     VARCHAR(max),    @split VARCHAR(10))RETURNS @re TABLE        (            Id INT IDENTITY(1,1),            Value VARCHAR(100)        )ASBEGIN    IF @s IS NULL        RETURN    IF @split IS NULL        RETURN    IF(LEN(@split)<=0)    BEGIN        INSERT INTO @re VALUES (@s)        RETURN    END    DECLARE @splitlen INT    SET @splitlen=LEN(@split ) - 1    WHILE CHARINDEX(@split, @s) > 0    BEGIN        INSERT @re VALUES(LEFT(@s, CHARINDEX(@split, @s) - 1))        SET @s=STUFF(@s, 1, CHARINDEX(@split, @s) + @splitlen, ‘‘)    END    INSERT @re VALUES(@s)    RETURNEND

 

 

 

测试脚本，没啥技术含量

CREATE TABLE TestColumnMergeAndSplit(    Id int Identity(1,1),    BusinessId int,    BusinessValue varchar(20))GOINSERT INTO TestColumnMergeAndSplitSELECT 1,‘AAA‘UNION ALLSELECT 1,‘BBB‘UNION ALLSELECT 1,‘CCC‘UNION ALLSELECT 2,‘XXX‘UNION ALLSELECT 2,‘YYY‘UNION ALLSELECT 2,‘ZZZ‘GOSELECT * FROM TestColumnMergeAndSplitGO--合并多列为一列SELECT  t1.BusinessId,       STUFF       (            ( SELECT     ‘,‘+t2.BusinessValue               FROM      TestColumnMergeAndSplit t2              WHERE     t2.BusinessId = t1.BusinessId              FOR XML PATH(‘‘)            ),            1,1,‘‘        )         AS ColStringFROM   TestColumnMergeAndSplit t1GROUP BY t1.BusinessIdGOSELECT * FROM TestColumnMergeAndSplit_BAKGOSELECT t1.BusinessId,t1.ColString,t2.Id,t2.Value FROM TestColumnMergeAndSplit_BAK t1    CROSS APPLY dbo.fn_SplitStringToTable(ColString,‘,‘)t2 GO

 

　　

T-SQL行合并成列与列拆分成行


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