SELECT [GROUP BY 절에 지정된 컬럼][집계될 값]
FROM 테이블명
ORDER BY [그룹으로 묶일 컬럼 값];
SELECT job, COUNT(job) FROM emp GROUP BY job;
SELECT deptno, COUNT(deptno)
FROM emp
GROUP BY deptno;
부서인원이 5명 이상인 부서 조회
SELECT e.deptno, dname, COUNT(e.empno)
FROM emp e, dept d
WHERE e.deptno = d.deptno
GROUP BY e.deptno, dname
HAVING COUNT(e.empno) > 5;