1. 외부 조인
SELECT DIStINCt M.mem_id, B.prod_name, M.mem_name, M.addr
FROM member M
LEFT OUTER JOIN buy B
ON M.mem_id = B.mem_id
WHERE B.prod_names IS NULL
ORDER BY M.mem_id;
smilegate
SELECT DIStINCt M.mem_id, B.prod_name, M.mem_name, M.addr
FROM member M
LEFT OUTER JOIN buy B
ON M.mem_id = B.mem_id
WHERE B.prod_names IS NULL
ORDER BY M.mem_id;