-------------------对分组统计的结果进一步筛选（having子句使用）------------------------------select * from student2010--1、查询qypt08class表中各院系的人数，只显示人数多于400的记录select yx,sum(rs) from qypt08class group by yx having sum(rs)>400 --2、统计stucou表中各门课程的选修人数,只显示人数少于30的记录(显示couno及对应的人数)select couno,count(*) from stucou group by couno having count(*)<30--3、查询student2010表中人数多于70人的班级的xymc、zymc、bjmc及rs（人数）select xymc,zymc,bjmc,count(*) from student2010 group by xymc,zymc,bjmc having count(*)>70