怎么写

如何写
一 二
--------------
A a
A b
A c
B 1
B 2
B 3


=======
期望得到结果

A a,b,c
B 1,2,3

[解决办法]

SQL code

select 一,二=stuff((select ','+ltrim(二) from tb where 一=t.一 for xml path('')),1,1,'')from tb tgroup by 一
[解决办法]
SQL code
if object_id('[tb]') is not null drop table [tb]gocreate table [tb]([一] varchar(1),[二] varchar(1))insert [tb]select 'A','a' union allselect 'A','b' union allselect 'A','c' union allselect 'B','1' union allselect 'B','2' union allselect 'B','3'goselect 一,二=stuff((select ','+ltrim(二) from tb where 一=t.一 for xml path('')),1,1,'')from tb tgroup by 一/**一    二---- --------------A    a,b,cB    1,2,3(2 行受影响)**/
[解决办法]
列值合并问题最近出现的特别多。

SQL code
--合并列值--原著：邹建--改编：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)  2007-12-16  广东深圳--表结构，数据如下：/*id    value ----- ------ 1    aa 1    bb 2    aaa 2    bbb 2    ccc */--需要得到结果：/*id    values ------ ----------- 1      aa,bb 2      aaa,bbb,ccc 即：group by id, 求value 的和（字符串相加）*/--1. 旧的解决方法(在sql server 2000中只能用函数解决。) --1. 创建处理函数create table tb(id int, value varchar(10)) insert into tb values(1, 'aa') insert into tb values(1, 'bb') insert into tb values(2, 'aaa') insert into tb values(2, 'bbb') insert into tb values(2, 'ccc') go create function dbo.f_str(@id int) returns varchar(8000) as begin     declare @r varchar(8000)     set @r = ''     select @r = @r + ',' + value from tb where id=@id     return stuff(@r, 1, 1, '') end go -- 调用函数SELECt id, value = dbo.f_str(id) FROM tb GROUP BY id drop table tb drop function dbo.f_str /* id          value      ----------- ----------- 1          aa,bb 2          aaa,bbb,ccc （所影响的行数为2 行）*/ --2、另外一种函数. create table tb(id int, value varchar(10)) insert into tb values(1, 'aa') insert into tb values(1, 'bb') insert into tb values(2, 'aaa') insert into tb values(2, 'bbb') insert into tb values(2, 'ccc') go --创建一个合并的函数create function f_hb(@id int) returns varchar(8000) as begin   declare @str varchar(8000)   set @str = ''   select @str = @str + ',' + cast(value as varchar) from tb where id = @id   set @str = right(@str , len(@str) - 1)   return(@str) End go --调用自定义函数得到结果：select distinct id ,dbo.f_hb(id) as value from tb drop table tb drop function dbo.f_hb /* id          value      ----------- ----------- 1          aa,bb 2          aaa,bbb,ccc （所影响的行数为2 行）*/ --2. 新的解决方法(在sql server 2005中用OUTER APPLY等解决。) create table tb(id int, value varchar(10)) insert into tb values(1, 'aa') insert into tb values(1, 'bb') insert into tb values(2, 'aaa') insert into tb values(2, 'bbb') insert into tb values(2, 'ccc') go -- 查询处理select * from(select distinct id from tb)a outer apply(         select [values]= stuff(replace(replace(             (                 select value from tb n                 where id = a.id                 for xml auto             ), ' <N value="', ','), '"/>', ''), 1, 1, '') )N drop table tb /* id          values ----------- ----------- 1          aa,bb 2          aaa,bbb,ccc (2 行受影响) */ --SQL2005中的方法create table tb(id int, value varchar(10)) insert into tb values(1, 'aa') insert into tb values(1, 'bb') insert into tb values(2, 'aaa') insert into tb values(2, 'bbb') insert into tb values(2, 'ccc') go select id, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '') from tb group by id /* id          values ----------- -------------------- 1          aa,bb 2          aaa,bbb,ccc (2 row(s) affected) */ drop table tb