LEFT JOIN, INNER JOIN , 차집합

left join / right join

SELECT t1.number, t1.name, t2.height, t2.weight
FROM mypokemon AS t1
LEFT JOIN ability AS t2
ON t1.number = t2.number;

 

SELECT *
FROM mypokemon
RIGHT JOIN ability
ON mypokemon.number = ability.number;

 

inner join - 두 테이블 모두에 있는 값만 합치기

 

OUTER JOIN , CROSS JOIN, SELF JOIN
UNION = 두 쿼리의 결과를 중복을 제외하고 합쳐서 보여주는 집합 연산자

MySQL에는 키워드가 없어서
LEFT JOIN UNION RIGHT JOIN

 

SELECT
FROM
LEFT JOIN
ON
UNION
SELECT
FROM
RIGHT JOIN
ON

Cross join

CROSS JOIN
SELECT
FROM
CROSS JOIN
WHERE

Self join

SELECT
FROM table_A AS t1
INNER JOIN table_A AS t2
ON t1.column=t2.

 

mission 1)
SELECT t1.name
FROM mypokemon AS t1
INNER JOIN friendpokemon AS t2
ON t1.number=t2.number ;

mission 2)
SELECT t1.name
FROM mypokemon AS t1
LEFT JOIN friendpokemon AS t2
ON t1.number=t2.number
WHERE t2.name IS NULL;