分组字符合并SQL语句按某字段合并字符串之一(简单合并)_Sql Server

分组字符合并SQL语句按某字段合并字符串之一(简单合并)

2020-05-16 18:11MSSQL教程网 Sql Server

这篇文章主要介绍了分组字符合并SQL语句按某字段合并字符串之一(简单合并),需要的朋友可以参考下

标题：按某字段合并字符串之一(简单合并)

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 int) 

									returns varchar(100)

									as

									begin

									declare @str varchar(1000) 

									set @str='' select @str=@str+''+cast(value as varchar) 

									from tb where id = @id 

									set @str=right(@str , len(@str) - 1) 

									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