And Exists To Merge Into

UPDATE DR_POS pos

set MtIntInterPer = (select max(MtFlx) from DR_ECH_OPE ech
where ech.DateCurrent = '03/01/2019' AND ech.IdOpe = pos.IdOpe AND ech.IdJmb = pos.IdJmb AND ech.CdTypOpe = pos.CdTypOpe AND ech.CdTypFlx in ('INT', 'IPR') 
and ech.DtVal=pos.DtProPaiInt)
where datecurrent = '03/01/2019' AND CdEtab = 'BPCE'
AND exists (select 1 from DR_ECH_OPE ech
where ech.DateCurrent = '03/01/2019' AND ech.IdOpe = pos.IdOpe AND ech.IdJmb = pos.IdJmb AND ech.CdTypOpe = pos.CdTypOpe AND ech.CdTypFlx in ('INT', 'IPR') 
and ech.DtVal=pos.DtProPaiInt )
AND exists (select 1 from DR_ECH_OPE ech
where ech.DateCurrent = '03/01/2019' AND ech.IdOpe = pos.IdOpe AND ech.IdJmb = pos.IdJmb AND ech.CdTypOpe = pos.CdTypOpe AND ech.CdTypFlx in ('INT', 'IPR') 
and DtFinPer=pos.DTARRETE);

محاولتي لاكن ليست سليمه:

Merge into DR_POS pos
using (select max(ech.MtFlx) max_mtflx ,ech.DateCurrent,ech.IdOpe,ech.IdJmb ,ech.CdTypOpe,ech.CdTypFlx,ech.DtVal, ech.DtFinPer from DR_ECH_OPE ech
where ech.DateCurrent = '03/01/2019' AND ech.CdTypFlx in ('INT', 'IPR') group by ech.DateCurrent, ech.IdOpe, ech.IdJmb, ech.CdTypOpe, ech.CdTypFlx, 
ech.DtVal, ech.DtFinPer ) ech
on((pos.datecurrent = '03/01/2019' AND pos.CdEtab = 'BPCE' and ech.IdOpe = pos.IdOpe AND ech.IdJmb = pos.IdJmb AND ech.CdTypOpe = pos.CdTypOpe 
and ech.DtVal=pos.DtProPaiInt ) and (ech.DateCurrent = '03/01/2019' AND ech.IdOpe = pos.IdOpe AND ech.IdJmb = pos.IdJmb AND ech.CdTypOpe = pos.CdTypOpe AND ech.CdTypFlx in ('INT', 'IPR') 
and ech.DtFinPer=pos.DTARRETE))

when matched then 
update set MtIntInterPer=max_mtflx ;

Merci