SQL LEFT JOIN 간단 예제: MySQL 에서 테스트. drop table A;drop table B; create table A(id int, val int);create table B(id int, val int); INSERT INTO A VALUES(1, 10);INSERT INTO A VALUES(2, 20);INSERT INTO A VALUES(3, 30); INSERT INTO B VALUES(1, 100);INSERT INTO B VALUES(2, 200);INSERT INTO B VALUES(3, 300); -- SELECT * FROM A;-- SELECT * FROM B; select a.*,b.*from A a left join B b -- from B b left join ..