第10天 sql 指令

接上篇
4、select * from student order by math desc/sak
5、聚合函数
（1）select count(id) from student
select count(*) from student
(2)select sum/avg(math) from student
(3)select max/min(math) from student
(4)select distinct(sex) from student

6、查询每个班级的数学总成绩
select sum(math) from student group by class

查询每个班数学总分大于100分的班级和总分数
select class,sum(math) from math group by class having sum(math)>100

查询每个班级性别为1的数学总分大于100的班级和总分数
select class,sum(math) from student where sex=1 group by class having sum(math)>100