2017-08-09 ■ MySQL RDBMS 【MySQL】集約関数GROUP_CONCAT(expr) SELECT id, user_id FROM group_members where id = 1 id user_id 1 1 1 2 1 3 1 4 SELECT id, group_concat(user_id separator ',') as members FROM group_members WHERE id = 1 GROUP BY id; id members 1 1,2,3,4