题解 | #分别满足两个活动的人#

SELECT * FROM (SELECT DISTINCT uid tid,'activity1' AS activity FROM exam_record WHERE YEAR(submit_time)=2021 AND score>=85 ) t1 UNION ALL SELECT * FROM (SELECT DISTINCT er.uid tid,'activity2'AS activity FROM exam_record er JOIN examination_info ei ON er.exam_id=ei.exam_id WHERE (UNIX_TIMESTAMP(er.submit_time)-UNIX_TIMESTAMP(er.start_time))/60<30 AND ei.difficulty='hard' AND er.score>80 AND YEAR(submit_time)=2021 )t2 ORDER BY tid ASC;