步步为营-89-SQL语句(删除重复数据)

--第一步:先找到重复数据
select ProcInstID from record_errorlog
group by ProcInstID
having count(ProcInstID) > 1
--查看一下
select * from record_errorlog 
where ProcInstID in (select ProcInstID from record_errorlog
group by ProcInstID
having count(ProcInstID) > 1);
--第二部 保留ErrorLogID最大的(也就是最新的数据)
delete  from record_errorlog 
where ProcInstID in (select ProcInstID from record_errorlog group by ProcInstID having count(ProcInstID) > 1)
and ErrorLogID not in (select max(ErrorLogID) from  record_errorlog group by ProcInstID having count(ProcInstID )>1);