select deptno, count(empno), sum(sal), avg(sal)
from emp
where deptno != 10
group by deptno
having count(empno) >= 3
order by count(empno) desc
delete from emp;
truncate table emp;
select e.ename,e.deptno,e.dname from emp as e
inner join dept as d
on e.deptno = d.deptno
select e.ename,e.deptno,d.dname from emp as e,
dept as d
where e.deptno = d.deptno
select e.ename, e.job, e.deptno, d.dname, d.loc
from emp as e
inner join dept as d
on e.deptno = d.deptno
where e.empno = 7788
select e.deptno, d.dname from emp as e
inner join dept as d
on e.deptno = d.deptno
group by e.deptno
select
e.ename as "사원 이름",
d.dname as "부서 번호",
d.loc as "부서 위치"
from emp as e
inner join dept as d
on e.deptno = d.deptno
where e.job = 'manager'
select * from dept as d
inner join emp as e
select * from dept where deptno = 40;
select * from dept as d left join emp as e
on d.deptno = e.deptno
where e.empno is null
select
boss.empno as '상사 번호',
boss.ename as '상사 이름',
underling.empno as '부하직원 번호',
underling.ename as '부하직원 이름'
from emp as boss
inner join emp as underling
on boss.empno = underling.mgr
insert into emp (empno, ename, job, sal, hiredate)
values (8000, '손흥민', 'SALESMAN', 7000, now());
select * from emp as e left join dept as d
on e.deptno = d.deptno
where d.dname is null
update emp
set sal = 8000
where empno = 8000