提一个常见的问题

[xiaoyi1981]

表A(id,Pid)
表A有如下记录
id Pid
1 01
1 02
2 03
2 02
2 05
怎么样实现
id Pid
1 01,02
2 02,03,05

[bqb]

create table test(id int,Pid varchar(20))
insert test(id,Pid)
select 1,'01'
union all
select 1,'02'
union all
select 2,'02'
union all
select 2,'03'
union all
select 2,'02'
union all
select 2,'05'

select * from test


id Pid
----------------
1 01
1 02
2 02
2 03
2 02
2 05



create function fmerg(@id int)
returns varchar(8000)
as
begin
declare @str varchar(8000)
set @str=''
select @str=@str+','+cast(pid as varchar) from test where id=@id
set @str=right(@str,len(@str)-1)
return(@str)
End
go

select distinct id,dbo.fmerg(id) Pid from test

id Pid
--------------
1 01,02
2 02,03,02,05


--刪除
drop table test
drop function dbo.fmerg

[davorsuker39]

create table ta (id int, value varchar(20))
Insert into ta
select '1','aaa'
union all select '2','bbb'
union all select '3','ccc'

create table tb (id int, value varchar(20))
Insert into tb
select '1','aaa,bbb,'
union all select '2','bbb,ccc,'
union all select '3','aaa,bbb,ccc,'

select * from ta
select * from tb

--函數
create function dbo.fn_m(@vchstring varchar(1000))
returns varchar(1000)
as
begin
declare @intstart int,@intlocation int
declare @s varchar(1000),@vchsubstring varchar(100)

select @intstart =1,@s=''
select @intlocation = charindex(',',@vchstring,@intstart)
while (@intlocation <>0 )
begin
select @vchsubstring=substring(@vchstring,@intstart,@intlocation-@intstart)
select @s=@s+cast([id] as varchar)+',' from ta where value=@vchsubstring
select @intstart = @intlocation +1
select @intlocation = charindex(',',@vchstring,@intstart)
end
return(@s)
end

--刪除
drop table ta
drop table tb
drop function dbo.fn_m

select id, value=dbo.fn_m(value) from tb
--結果
id value
------------------
1 1,2,
2 2,3,
3 1,2,3,

[lipkissnow]

學習

[lipkissnow]

我曾想用游標來寫.但看到上面大家給出的是用函數的.我就想到一個問題是.用游標寫和用函數哪一個消耗系統資源最少.

[Andy__Huang]

參考﹕

--建表
create table tb (A varchar(10),B varchar(1000))
Insert into tb
select '111','AA0000，AA0001，AA0002，'
union all select '111','BB0000，BB0001，BB0002，'
union all select '222','AA0120，AA0102，AA1453，'
union all select '222','BB1212，BB3423，BB2123，'

select * from tb

--函數
create function dbo.fn_b(@a varchar(10))
returns varchar(1000)
as
begin
declare @s varchar(1000)
set @s=''
select @s=@s+[B] from tb where A=@a
return (@s)
end

--刪除
drop table tb
drop function dbo.fn_b

--結果
select A,B=dbo.fn_b(A) from tb group by A
A B
-------------------------------------------
111 AA0000，AA0001，AA0002，BB0000，BB0001，BB0002，
222 AA0120，AA0102，AA1453，BB1212，BB3423，BB2123，