select * from cfg_ag_iad a
where (a.agip,a.agid,a.relationtype) in (select agip,agid,relationtype from cfg_ag_iad group by agip,agid,relationtype having count(*)>1)
and updatetime not in (select max(updatetime) from cfg_ag_iad group by agip,agid having count(*) >1)

select agip,agid,relationtype,updatetime from 
(select agip,
agid,
relationtype,
updatetime,
row_number()over(partition by agip,agid,relationtype order by updatetime desc) rn
from cfg_ag_iad)
where rn>1

------解决方案--------------------
SQL code

试试这个吧，可以滴
delete from 
--select * 
from cfg_ag_iad t 
where (agip,agid,relationtype,updatetime) not in (
  select a.agip,a.agid,a.relationtype,max(updatetime) updatetime
  from cfg_ag_iad a 
  group by a.agip,a.agid,a.relationtype
)

------解决方案--------------------
--查询出你要的数据
select *
 from cfg_ag_iad a
  where (a.agip, a.agid, a.relationtype) in
      (select agip, agid, relationtype
         from cfg_ag_iad
        group by agip, agid, relationtype
       having count(*) > 1)
  and updatetime in (select max(updatetime) as updatetime, agip, agid, relationtype
                           from cfg_ag_iad
                          group by agip, agid, relationtype
                         having count(*) > 1)
                        
--在数据库保留你要的数据                         
delete from from cfg_ag_iad a
  where (a.agip, a.agid, a.relationtype) in
      (select agip, agid, relationtype
         from cfg_ag_iad
        group by agip, agid, relationtype
       having count(*) > 1)
  and updatetime not in (select max(updatetime) as updatetime, agip, agid, relationtype
                           from cfg_ag_iad
                          group by agip, agid, relationtype
                         having count(*) > 1)