Javaweb-DQL-分组查询

1. select sex,avg(math) from stu group by sex;
2. select sex,avg(math),count(*) from stu group by sex;
3. select sex,avg(math),count(*) from stu where math>=70 group by sex;
4. select sex,avg(math),count(*) from stu where math>=70 group by sex having count(*) > 2;