select 한 col을 값들로 그룹화 한다.
select deptno,count(*),sum(sal), avg(sal)
from emp
group by deptno
order by deptno;
select job,deptno,count(*),sum(sal), avg(sal)
from emp
group by job,deptno
order by deptno;
group by
로 집계된 데이터를 having 조건
으로 필터링함
그럼 group by
와 having
의 차이는 뭘까?
where
절은 묶기 전에 조건으로 필터링함having
절은 묶고 난 후 조건으로 필터링함select team_id, avg(height)
from player
group by team_id
order by avg(height);
select team_id, avg(height)
from player
group by team_id
having avg(height) > 180
order by avg(height);