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create function [dbo].[f_str](@a varchar(20),@b varchar(20))
returns varchar(8000)
as
begin
declare @s varchar(8000)
select @s=isnull(@s+'_','')+ltrim(c)
from tb
where a=@a and b=@b order by tb.created desc
return @s
end
create function [dbo].[f_str](@a varchar(20),@b varchar(20))
returns varchar(MAX)
as
begin
declare @s varchar(MAX)
select @s=isnull(@s+'_','')+ltrim(c)
from tb
where a=@a and b=@b order by tb.created desc
return @s
end
create table # (a int, b int, c varchar(8000), create_date datetime)
insert # select 1,1, 'a', 0
insert # select 1,1, 'b', 1
insert # select 1,2, 'c', 2
insert # select 1,2, 'd', 3
declare @ varchar(max)
select @ = isnull(@+'_', '') + ltrim(c) from # where a=1 and b=1 order by create_date desc
select @ -- b_a
/*
这里没有问题
你看看函数的执行计划,要不把缓存清一下试试
*/
/*
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')
go
create 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 id
drop 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')
go
select id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')
from tb
group by id
drop 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_cursor
select * from @t
drop table tb
最好给出完整的表结构,测试数据,计算方法和正确结果.否则耽搁的是你宝贵的时间。
如果有多表,表之间如何关联?
declare @s varchar(8000)
select @s=isnull(@s+'_','')+ltrim(c)
from (select 2 as c union all select 3) temp
select @s
go
declare @s varchar(max)
select @s=isnull(@s+'_','')+ltrim(c)
from (select 2 as c union all select 3) temp
select @s
你想证明什么呢?
--贴出你的数据和结果,顺便拿来ID、IC...卡和密码。
alter function [dbo].[f_str](@a varchar(20),@b varchar(20))
returns varchar(MAX)
as
begin
return stuff((select '_'+ltrim(c) from tb where a=@a and b=@b order by tb.created desc for xml path('')), 1, 1, '')
end