---->>TravyLee生成测试数据
if OBJECT_ID('Course')is not null
drop table Course
go
create table Course(
CouID int,
CouType varchar(10)
)
go
insert Course
select 1,'Java' union all
select 2,'SQL Server' union all
select 3,'HTML5'
if OBJECT_ID('CouBooked')is not null
drop table CouBooked
go
create table CouBooked(
BookedID int,
CouID int,
CouType varchar(10)--不明白为什么还要一个课程类型
)
go
insert CouBooked
select 1,1,'test1' union all
select 2,1,'test2' union all
select 3,3,'test3' union all
select 4,2,'test4' union all
select 5,1,'test5' union all
select 6,1,'test6' union all
select 7,2,'test7' union all
select 8,2,'test8' union all
select 9,2,'test9' union all
select 10,1,'test10' union all
select 11,3,'test11' union all
select 12,1,'test12'
go


select 
    CouID,CouType
from
    Course
where 
    CouID in(
select 
    CouID
from(
select 
    CouID,COUNT(CouID) as Times 
from 
    CouBooked 
group by 
    CouID
having COUNT(CouID)>=4
    )t
    )
/*
CouID    CouType
--------------------------
1    Java
2    SQL Server
*/