有一个表中的数据为:
declare @T table(afield varchar(50), bfield varchar(100))
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'现需要用1条不带函数的SQL语句得到如下结果:
a asd,rdf,dmg
b kk,useh注意:由于开发实际情况,需要直接用SQL语句查询出结果,不能使用函数来得到bfield的字符级联。
也就是说不能用如下的语句:
Select afield, dbo.getstr(afield) from @T
Group by afield
declare @T table(afield varchar(50), bfield varchar(100))
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'现需要用1条不带函数的SQL语句得到如下结果:
a asd,rdf,dmg
b kk,useh注意:由于开发实际情况,需要直接用SQL语句查询出结果,不能使用函数来得到bfield的字符级联。
也就是说不能用如下的语句:
Select afield, dbo.getstr(afield) from @T
Group by afield
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'
select distinct afield,bfield=stuff((select ','+rtrim(bfield)
from @T where afield=t.afield for xml path('')),1,1,'') from @T t
/*
afield bfield
---------------------
a asd,dmg,rdf
b kk,useh
*/
declare @T table(afield varchar(50), bfield varchar(100))
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'Select afield from @T
SELECT a.afield,
status =stuff((
select ','+convert(varchar(20),bfield) FROM @T WHERE afield = a.afield for xml path(''))
,1,1,'')
FROM @T a
group by a.afield
declare @T table(afield varchar(50), bfield varchar(100))
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'select a.afield,stuff((select ','+b.bfield from @t as b where a.afield = b.afield for xml path('')),1,1,'') as res
from @t a
group by a.afield
结果
a asd,dmg,rdf
b kk,useh
Insert into T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'select a.afield,stuff((select ','+b.bfield from t as b where a.afield = b.afield
for xml path('')),1,1,'') as bfield
from t a
group by a.afieldafield bfield
---------------------------------
a asd,dmg,rdf
b kk,useh(2 row(s) affected)
标题:按某字段合并字符串之一(简单合并)
作者:爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)
时间:2008-11-06
地点:广东深圳描述:将如下形式的数据按id字段合并value字段。
id value
----- ------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
需要得到结果:
id value
------ -----------
1 aa,bb
2 aaa,bbb,ccc
即:group by id, 求 value 的和(字符串相加)
*/
--1、sql2000中只能用自定义的函数解决
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')
gocreate function dbo.f_str(@id varchar(10)) returns varchar(1000)
as
begin
declare @str varchar(1000)
select @str = isnull(@str + ',' , '') + cast(value as varchar) from tb where id = @id
return @str
end
go--调用函数
select id , value = dbo.f_str(id) from tb group by iddrop function dbo.f_str
drop table tb
--2、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')
goselect id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')
from tb
group by iddrop table tb
--3、使用游标合并数据
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
declare @t table(id int,value varchar(100))--定义结果集表变量
--定义游标并进行合并处理
declare my_cursor cursor local for
select id , value from tb
declare @id_old int , @id int , @value varchar(10) , @s varchar(100)
open my_cursor
fetch my_cursor into @id , @value
select @id_old = @id , @s=''
while @@FETCH_STATUS = 0
begin
if @id = @id_old
select @s = @s + ',' + cast(@value as varchar)
else
begin
insert @t values(@id_old , stuff(@s,1,1,''))
select @s = ',' + cast(@value as varchar) , @id_old = @id
end
fetch my_cursor into @id , @value
END
insert @t values(@id_old , stuff(@s,1,1,''))
close my_cursor
deallocate my_cursorselect * from @t
drop table tb
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'
select distinct afield,bfield=stuff((select ','+rtrim(bfield)
from @T where afield=t.afield for xml path('')),1,1,'') from @T t
/*
afield bfield
---------------------
a asd,dmg,rdf
b kk,useh
*/
不能用函数,是因为效率太低的问题. 本来想用临时表,再用1条SQL来提高速度, 看来得另想办法了.:)
--有一个表中的数据为:
declare @T table(afield varchar(50), bfield varchar(100))
Insert @T
Select 'a', 'asd' union
Select 'a', 'rdf' union
Select 'a', 'dmg' union
Select 'b', 'kk' union
Select 'b', 'useh'declare @T2 table(afield varchar(50), bfield varchar(100),cfield varchar(1000))
insert into @t2 (afield,bfield)
select distinct afield,'' from @t
update a
set bfield=(select top 1 bfield from @t where afield=a.afield order by bfield),
cfield=(select top 1 bfield from @t where afield=a.afield order by bfield)
from @t2 a
while exists(select * from @t a,@t2 b where a.afield=b.afield and a.bfield>b.bfield)
begin
update a
set bfield=(select top 1 bfield from @t where afield=a.afield and bfield>a.bfield order by bfield),
cfield=a.cfield+','+(select top 1 bfield from @t where afield=a.afield and bfield>a.bfield order by bfield)
from @t2 a where exists(select * from @t where afield=a.afield and bfield>a.bfield)
endselect afield,cfield from @t2