mysql删除重复记录只保留一条数据

delete a from orderinfocontent a ,(select c.ordertrackno,max(c.id) as bid
 from orderinfocontent c group by ordertrackno having count(1) > 1)
  b where a.ordertrackno = b.ordertrackno and a.id<b.bid;


(上述MySQL删除重复的数据,只保留ID最大的那条数据)
(整理出自己用过的)