字符串拆分,修改,再合并

假设有2个表，需要组成一个视图，分别如下：

表1: [Tags]

ID Name
------------------------------
1 Tag1
2 Tag2
3 Tag3
4 Tag4
5 Tag5
...

表2：[Test]

ID Title TagID
------------------------------
1 标题1 1,4
2 标题2 1,3,4
3 标题3 2,5
4 标题4 3,4
5 标题5 2,3,4,5
...

如上例，如建立一个视图，并根据表[Test]的[TagID]字段的数组，关联表[Tags]的[Name]字段对应的行，得到如下视图：

视图1：[View_Test]

ID Title Tags
-----------------------------
1 标题1 Tag1,Tag4
2 标题2 Tag1,Tag3,Tag4
3 标题3 Tag2,Tag5
4 标题4 Tag3,Tag4
5 标题5 Tag2,Tag3,Tag4,Tag5

------------------------------------------------------------------------------------------------------------------------------------

解决思路:是先把字符串按逗号拆了，再根据tags表修改，最后再合并

if object_id('tempdb..#') is not null
drop table #
if object_id('tempdb..#t') is not null
drop table #t
if object_id('tempdb..#tb') is not null
drop table #tb
--按逗号分割
select top 2000 id=identity(int,1,1) into # from syscolumns a,syscolumns b
select a.id,a.title,tagid=substring(a.tagid,b.id,charindex(',',a.tagid+',',b.id)-b.id) into #t
from test a, # b
where substring(','+a.tagid,b.id,1)=',' order by a.id,b.id
--更新
update #t
set tagid=b.name
from #t a,tags b
where a.tagid=b.id
--合并
select *,cast(',' as varchar(8000)) as aa into #tb from #t order by id,tagid
declare @id int,@name varchar(50)
update #tb
set @name=case @id when id then @name+','+tagid else tagid end,aa=@name,@id=id
select id,title,max(aa) as tagid from #tb group by id,title