optimize sql statement

Hello,

How can I optimize this query :
select DAA.ZORIDOS_0,'DAA-', DAA.CPY_0, sum(DAA.AMTCUR_0*DAE.SNS_0)
from ODS1.GACCENTRYA DAA,
     ODS1.GACCENTRYD DAE,
     ODS1.GACCENTRY  HAE
where DAE.ZORIDOS_0=DAA.ZORIDOS_0
and   DAE.TYP_0=DAA.TYP_0
and   DAE.NUM_0=DAA.NUM_0
and   DAE.LIG_0=DAA.LIG_0
and   DAE.SNS_0=-1
and   HAE.ZORIDOS_0=DAE.ZORIDOS_0
and   HAE.TYP_0=DAA.TYP_0
and   HAE.NUM_0=DAA.NUM_0
group by DAA.ZORIDOS_0,DAA.CPY_0

The cost of join between GACCENTRYA et GACCENTRYD is very high.

Thanks

Regards

bibi