陈可

摘要： 1.查询多列重复SELECT * FROM zd_isstory_log a WHERE (a.class_id,a.lesson_id,a.course_id) IN (SELECT class_id,lesson_id,course_id FROM zd_isstory_log GROUP BY class_id,lesson_id,course_id HAVING COUNT(*) > 1) ;2.删除重复数据（保留id小的数据）CREATE TABLE tmp ASSELECT * FROM zd_isstory_log a WHERE (a.class_id,a.lesson_ 阅读全文