怎么让分割字符

如何让分割字符？
现在一个表中有这样一些数据
a b
1 1,2
1 2,3
2 1,2
2 2,3
3 1,2
3 2,3


我想把a和b不相同的数据合并，然后去除b字段中出现重复的信息
结果如下
a b
1 1,2,3
2 1,2,3
3 1,2,3

[解决办法]
如果是sql 2000,则如下两个例合起来做.

SQL code

/*标题：简单数据拆分(version 2.0)作者：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)时间：2010-05-07地点：重庆航天职业学院描述：有表tb, 如下:id          value----------- -----------1           aa,bb2           aaa,bbb,ccc欲按id,分拆value列, 分拆后结果如下:id          value----------- --------1           aa1           bb2           aaa2           bbb2           ccc*/--1. 旧的解决方法(sql server 2000)create table tb(id int,value varchar(30))insert into tb values(1,'aa,bb')insert into tb values(2,'aaa,bbb,ccc')go--方法1.使用临时表完成SELECT TOP 8000 id = IDENTITY(int, 1, 1) INTO # FROM syscolumns a, syscolumns b SELECT A.id, value = SUBSTRING(A.[value], B.id, CHARINDEX(',', A.[value] + ',', B.id) - B.id)FROM tb A, # BWHERE SUBSTRING(',' + A.[value], B.id, 1) = ','DROP TABLE #--方法2.如果数据量小，可不使用临时表select a.id , value = substring(a.value , b.number , charindex(',' , a.value + ',' , b.number) - b.number) from tb a join master..spt_values  b on b.type='p' and b.number between 1 and len(a.value)where substring(',' + a.value , b.number , 1) = ','--2. 新的解决方法(sql server 2005)create table tb(id int,value varchar(30))insert into tb values(1,'aa,bb')insert into tb values(2,'aaa,bbb,ccc')go--方法1.使用xml完成SELECT A.id, B.value FROM(  SELECT id, [value] = CONVERT(xml,'<root><v>' + REPLACE([value], ',', '</v><v>') + '</v></root>') FROM tb) A OUTER APPLY(  SELECT value = N.v.value('.', 'varchar(100)') FROM A.[value].nodes('/root/v') N(v)) B--方法2.使用CTE完成;with tt as (select id,[value]=cast(left([value],charindex(',',[value]+',')-1) as nvarchar(100)),Split=cast(stuff([value]+',',1,charindex(',',[value]+','),'') as nvarchar(100)) from tbunion allselect id,[value]=cast(left(Split,charindex(',',Split)-1) as nvarchar(100)),Split= cast(stuff(Split,1,charindex(',',Split),'') as nvarchar(100)) from tt where split>'')select id,[value] from tt order by id option (MAXRECURSION 0)DROP TABLE tb/*id          value----------- ------------------------------1           aa1           bb2           aaa2           bbb2           ccc(5 行受影响)*/
[解决办法]
经常用可以写一个函数.字符长度长时用函数也是一个比较好解决方法

SQL code
--> --> (Roy)生成測試數據 if not object_id('Tab') is null    drop table TabGoCreate table Tab([a] int,[b] nvarchar(1000))Insert Tabselect 1,N'1,2,3,1,4,5,6,7,7' union allselect 1,N'2,3' union allselect 2,N'1,2' union allselect 2,N'2,3' union allselect 3,N'1,2' union allselect 3,N'2,3'Goif OBJECT_ID('fn_split','FN') is not null    drop function fn_splitgoCreate function fn_split(@a int)returns nvarchar(1000)asbegin    declare @s nvarchar(1000),@s2 nvarchar(1000),@i int,@split nvarchar(100)    select @s=isnull(@s+',','')+b,@s2='' from Tab where a=@a    select @i=charindex(',',@s),@s2=left(@s,@i),@s=replace(@s+',',@s2,''),@i=charindex(',',@s)    while @i>0    begin        Select @split=left(@s,@i),@s2=@s2+@split,@s=replace(@s,@split,''),@i=charindex(',',@s)    end    return left(@s2,len(@s2)-1)endgoselect [a],dbo.fn_split(a) as b from Tab group by [a]/*a    b1    1,2,3,4,5,6,72    1,2,33    1,2,3*/