一、问题
groupBY分组后取最新一条记录的SQL的解决方案。
二、解决方案
select Message,EventTime from PT_ChildSysAlarms as a where EventTime = (select max(b.EventTime) from PT_ChildSysAlarms as b where a.PtName = b.PtName ) group by Message,EventTime order by EventTime desc
原文：https://www.cnblogs.com/songxingzhu/p/11941654.html