MySQL review 03-paging query + summary

1. Paging query

# 从0开始，长度为5
select * from employees limit 0,5;

2. Summary

2.1 DQL

// 查询哪个年级学生最小年龄>20岁
select minag.gradId,minag.minAge
from( select min(age) minAge,gradeId
from stuinfo
group by gradId) minag
where minag.minAge>20;