SELECT tag, COUNT(*) AS tag_cnt FROM exam_record t1 LEFT JOIN examination_info t2 ON t1.exam_id = t2.exam_id WHERE uid IN ( SELECT uid FROM exam_record WHERE submit_time IS NOT NULL GROUP BY DATE_FORMAT(submit_time, "%Y%m"), uid HAVING COUNT(*) >= 3 ) GROUP BY tag ORDER BY tag_cnt DESC; 试了两次，运行成功...
