SQL JOIN문 공부하기

 

1) INNER JOIN : 교집합

SELECT *
FROM A a , B b
WHERE a.KEY = b.KEY

SELECT *
FROM A a
INNER JOIN B b
ON a.KEY = b.KEY

2) LEFT OUTER JOIN : 부분집합

SELECT *
FROM A a
LEFT OUTER JOIN B b
ON a.KEY = b.KEY

3) RIGHT OUTTER JOIN : 부분집합

SELECT *
FROM A a
RIGHT OUTER JOIN B b
ON a.KEY = b.KEY

4) RIGHT ONLY JOIN
SELECT *
FROM A a
RIGHT JOIN B b
ON a.KEY = b.KEY
WHERE a.KEY IS NULL

5) LEFT ONLY JOIN

SELECT *
FROM A a
LEFT JOIN B b
ON a.KEY = b.KEY
WHERE b.KEY IS NULL

6) FULL OUTER JOIN : 합집합
SELECT *
FROM A a
FULL OUTER JOIN B b
ON a.KEY = b.KEY

참고 사이트
https://hongong.hanbit.co.kr/sql-%EA%B8%B0%EB%B3%B8-%EB%AC%B8%EB%B2%95-joininner-outer-cross-self-join/

SQL 기본 문법: JOIN(INNER, OUTER, CROSS, SELF JOIN)