create table employee(
eid int(15) primary key auto_increment,
ename varchar(20) not null,
salary float(9,2) not null,
deptid int(15) not null
);
select * from employee order by deptid desc,salary;
select avg(salary) from employee group by deptid;
select * from employee group by deptid desc,salary;
select * from employee group by deptid desc;