求解
两张表,有两个字段
table1
a1 a2
---------------------------
1 null
2 null
3 null
=====================================
table2
f0 f1
----------------------------------
1 a
1 b
1 c
2 a
2 e
3 f
我现在想求一个 update语句,update table1 set a2 = …………得到如下结果(也就是把f0相同的f2,填到f1里)
a1 a2
-------------------------
1 a,b,c
2 a,e
3 f
两张表,有两个字段
table1
a1 a2
---------------------------
1 null
2 null
3 null
=====================================
table2
f0 f1
----------------------------------
1 a
1 b
1 c
2 a
2 e
3 f
我现在想求一个 update语句,update table1 set a2 = …………得到如下结果(也就是把f0相同的f2,填到f1里)
a1 a2
-------------------------
1 a,b,c
2 a,e
3 f
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
2005直接xml2000:
create function f_str(@f0 int)
returns varchar(1000)
as
begin
declare @s varchar(1000)
select @s = isnull(@s,'')+','+f1 from table2 where f0 = @f0
return @s
end
go
use PracticeDB
go
if exists(select 1 from sysobjects where name='tb_a')
drop table tb_a
go
create table tb_a (a1 int, a2 varchar(20))
insert into tb_a
select 1, null union all
select 2, null union all
select 3, null
go
if exists(select 1 from sysobjects where name='tb_b')
drop table tb_b
go
create table tb_b (f0 int, f1 varchar(20))
insert into tb_b
select 1, 'a' union all
select 1, 'b' union all
select 1, 'c' union all
select 2, 'a' union all
select 2, 'e' union all
select 3, 'f';with t
as
(
select f0,stuff((select ','+f1
from tb_b
where a.f0=f0 for xml path('')),1,1,'') f
from tb_b a
group by f0
)
update tb_a set a2=t.f from t where a1=t.f0select * from tb_a
a1 a2
1 a,b,c
2 a,e
3 f