테이블 생성 코드 Create table If Not Exists Users (user_id int, user_name varchar(20)) Create table If Not Exists Register (contest_id int, user_id int) Truncate table Users insert into Users (user_id, user_name) values ('6', 'Alice') insert into Users (user_id, user_name) values ('2', 'Bob') insert into Users (user_id, user_name) values ('7', 'Alex') Truncate table Register insert into Register (conte..