SQL 将一个字段内用逗号分隔的内容分成多条记录

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本文转http://www.mhzg.net/a/20117/2011789260293.html

由于业务需求，我们可能会把一串以分割符字符串数据放到一个字段，如我们在客户端处理拆分是很简单的，不过这样做效果不太好，怎么用SQL SERVER 2008 来解决这件事件哪？

--参考 
 拆分表: 
  
 --> --> (Roy)生成測試數據 
   
 if not object_id('Tab') is null 
     drop table Tab 
 Go 
 Create table Tab([Col1] int,[COl2] nvarchar(5)) 
 Insert Tab 
 select 1,N'a,b,c' union all 
 select 2,N'd,e' union all 
 select 3,N'f' 
 Go 
  
 SQL2000用辅助表: 
 if object_id('Tempdb..#Num') is not null 
     drop table #Num 
 go 
 select top 100 ID=Identity(int,1,1) into #Num from syscolumns a,syscolumns b 
 Select  
     a.Col1,COl2=substring(a.Col2,b.ID,charindex(',',a.Col2+',',b.ID)-b.ID)  
 from  
     Tab a,#Num b 
 where 
     charindex(',',','+a.Col2,b.ID)=b.ID --也可用 substring(','+a.COl2,b.ID,1)=',' 
  
  
 SQL2005用Xml: 
  
 select  
     a.COl1,b.Col2 
 from  
     (select Col1,COl2=convert(xml,' <root> <v>'+replace(COl2,',',' </v> <v>')+' </v> </root>') from Tab)a 
 outer apply 
     (select Col2=C.v.value('.','nvarchar(100)') from a.COl2.nodes('/root/v')C(v))b 
  
  
 SQL05用CTE: 
  
 ;with roy as  
 (select Col1,COl2=cast(left(Col2,charindex(',',Col2+',')-1) as nvarchar(100)),Split=cast(stuff(COl2+',',1,charindex(',',Col2+','),'') as nvarchar(100)) from Tab 
 union all 
 select Col1,COl2=cast(left(Split,charindex(',',Split)-1) as nvarchar(100)),Split= cast(stuff(Split,1,charindex(',',Split),'') as nvarchar(100)) from Roy where split>'' 
 ) 
 select COl1,COl2 from roy order by COl1 option (MAXRECURSION 0) 
  
 生成结果: 
 /* 
 Col1        COl2 
 ----------- ----- 
 1           a 
 1           b 
 1           c 
 2           d 
 2           e 
 3           f 
 */