SQL join with distinct

I would like to run the following, but reduce the "B" file down to distinct key values PRIOR to the join.

Can this be accomplished in one SQL step?



select a.* from miscchg A, miscchgtmp B
where a.ASHPNBR = b.ashpnbr
and a.ABLDNGD = b.ABLDNGD



Maybe using "IN"? But that only works with one column, not two as I need.

Thanks!



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