表字段包括:用户id,年,月,日
CREATE TABLE `a` ( `user_id` int(11) NOT NULL, `day` int(10) NOT NULL, `month` int(10) DEFAULT NULL, `year` int(10) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
请查询在2020年每个月都有记录的用户id?
SELECT user_id FROM (SELECT user_id FROM a WHERE year = 2020 GROUP BY user_id , month) b GROUP BY user_id HAVING COUNT(user_id) = 12;
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