1、男学生出生日期的最大值和最小值:
SELECT select max(sBirthday),min(sBirthday) from student where sSex='男'
2、平均成绩
select avg(english) from score
select sum(sAge) as 年龄和 from student
5、count求个数和
select count(*) as 总人数 from student
聚合函数不能出现在Where字句中