你的位置:首页 > 数据库

[数据库]利用SQl对数据库实行数据拆分与组合


 利用SQl对数据库实行数据拆分与组合实现提供以下几种方案:

方法一:

WITH CTE AS (
SELECT A.Id,A.[Uid],UserName FROM (
SELECT A.[id], REPLACE(Split.a.value('.', 'NVARCHAR(max)'),'''','') AS [Uid]
FROM 
(
SELECT [id], CAST ('<M>' + REPLACE(Uid, ',', '</M><M>') + '</M>' AS ) AS A CROSS APPLY [Uid].nodes ('/M') AS Split(a)

) A INNER JOIN dbo.B B ON A.[Uid]=B.[Uid]
)
SELECT DISTINCT classList=stuff((select ',' +UserName from CTE B WHERE A.Id=B.Id for

 方法二:

SELECT t.id,classList=STUFF((
SELECT ','+tt1.UserName 
FROM A tt left join B tt1 ON ''+tt.Uid+',' like '%'+tt1.Uid+',%' 
WHERE tt.id=t.id FOR FROM A t 
ORDER BY t.id

方法三:

select id, (select UserName from B where Uid=t02.item) c into #ttt from dbo.A as t01 cross apply dbo.split(t01.Uid,',') as t02

select id,stuff((select ','+c from dbo.#ttt as tb01 where tb01.id=tb02.id for

from dbo.#ttt as tb02 group by id

drop table #ttt

方法三需要添加内置方法:

create function split(
@string varchar(255),
@separator varchar(255)
)returns @array table(item varchar(255))
as
begin
declare @begin int,@end int,@item varchar(255)
set @begin = 1
set @end=charindex(@separator,@string,@begin)
while(@end<>0)
begin
set @item = substring(@string,@begin,@end-@begin)
insert into @array(item) values(@item)
set @begin = @end+1
set @end=charindex(@separator,@string,@begin)
end
set @item = substring(@string,@begin,len(@string)+1-@begin)
if (len(@item)>0)
insert into @array(item) values(substring(@string,@begin,len(@string)+1-@begin))
return
end

下面们直接看结果吧:

表A:

表B:

最终结果:

跟根据讨论给出的方法,我个人给出这样的三种,如果有不对之处,请多多指教。

在这里我就不多文字咯,因为博客里面写再多文字别人看的时候都是看看最终是不是别人要的效果,是就学习不是直接拉到,欢迎各位朋友多多指教。