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
sql group by 分组取最新一条记录
免责声明！
本站转载的文章为个人学习借鉴使用，本站对版权不负任何法律责任。如果侵犯了您的隐私权益，请联系本站邮箱yoyou2525@163.com删除。