sqlserver 循环查询

在项目中。碰到一个问题。。

如下图。蓝色的如公务员、基础教育等属于一张表Category。小黑色的是从表TB_Classinfo中查出。两者通过category对应。通过一条sql语句实现。如下

with topc AS
(
 SELECT * from(
 select top 4  ROW_NUMBER() over (order by Orders desc) as rownum,ID from Category_30
 ) t1
)
select t.Class_Name,t.CreateTime,b.CategoryName from (
select top 5 Class_Name,Category,CreateTime from TB_ClassInfo
where  Category in (select id from topc where rownum=1)
union
select top 5  Class_Name,CreateTime from TB_ClassInfo
where  Category in (select id from topc where rownum=2)
union
select top 5 Class_Name,CreateTime from TB_ClassInfo
where  Category in (select id from topc where rownum=3)
union
select top 5 Class_Name,CreateTime from TB_ClassInfo
where  Category in (select id from topc where rownum=4)
) t
inner join Category_30 b
on t.Category=b.ID

简单方式：但是不能保证每一个分类都是取得5条数据。

select top 20 t.Class_Name,b.CategoryName from (
select Class_Name,CreateTime from TB_ClassInfo
where  Category in (SELECT ID from(
 select top 4  ROW_NUMBER() over (order by Orders desc) as rownum,ID from Category_30
 order by Orders desc) t1)
) t
inner join Category_30 b
on t.Category=b.ID