create table A(id int,name varchar(10),date datetime)
insert into a values(1 ,'a', '2009-8-1 15:10:03')
insert into a values(2 ,'b', '2009-8-1 15:10:03')
insert into a values(3 ,'c', '2009-8-2 15:10:03')
insert into a values(4 ,'d', '2009-8-2 15:10:03')
goselect m.* , n.* from a m , a n
where m.date = n.date and m.id < n.iddrop table a /*
id name date id name date
----------- ---------- ------------------------------------------------------ ----------- ---------- ------------------------------------------------------
1 a 2009-08-01 15:10:03.000 2 b 2009-08-01 15:10:03.000
3 c 2009-08-02 15:10:03.000 4 d 2009-08-02 15:10:03.000（所影响的行数为 2 行）
*/有可能实现 name等于 ab这样的值吗？。。
就是相同行的，把name2个值加一起。
变成ab....
from a
group by date /*
date name
------------------------------------------------------ -----------
2009-08-01 15:10:03.000 ab
2009-08-02 15:10:03.000 cd（所影响的行数为 2 行）*/
create table A(id int,name varchar(10),date datetime)
insert into a values(1 ,'a', '2009-8-1 15:10:03')
insert into a values(2 ,'b', '2009-8-1 15:10:03')
insert into a values(3 ,'c', '2009-8-2 15:10:03')
insert into a values(4 ,'d', '2009-8-2 15:10:03')
goselect m.id , n.id , m.name + n.name name , m.date from a m , a n
where m.date = n.date and m.id < n.iddrop table a
/*
id id name date
----------- ----------- -------------------- ------------------------------------------------------
1 2 ab 2009-08-01 15:10:03.000
3 4 cd 2009-08-02 15:10:03.000（所影响的行数为 2 行）
*/还是这样?
/*
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