测试派 Give testers a home.

本节课作业：
#6 查询出语文最高分
select Max(score) from SC b
inner join Course c on b.Cno=c.Cno
where c.Cname="语文";
#8 查询语数外三门成绩的平均分
select avg(score) from sc b
inner join course c on b.Cno=c.Cno
group by c.Cno
#9 查询报名孤独求败老师课程的学生信息
select * from teacher d
inner join course c on d.Tno=c.Tno
and d.Tname="孤独求败"
inner joinsc b on c.Cno=b.Cno
right join Student a on a.Sno=b.Sno;

根据课上的emp和dept表完成下列作业：
1、查询张姓员工的员工信息和所在部门信息。
select * from emp as a inner join dept as b on a.dept_id=b.id
where a.name like "张%";
2、查询张三丰管理了几个员工
select count(*) from emp as a inner join emp as b on a.id=b.leader where a.name="张三丰" and b.is_enable=1;
3、查询出所有实习员工（实习员工无部门信息）
select * from emp as a left join dept as b on a.dept_id=b.id
where b.id is null and is_enable=1;