Oracle中子查询的使用实例

找出所有姓“王”的各学生平均分比所有姓“李”的各学生平均分高的学生成绩统计信息。
select studno,avg(studscore) from studscoreinfo
where studno in (select studno from studinfo where studname like '王%')
group by studno
having avg(studscore)>all
(
select avg(studscore) from studscoreinfo
where studno in (select studno from studinfo where studname like '李%')
group by studno
)