I'm trying to add a status column to a select statement based on the contents of a different file. I'm trying to pull the customer number from the customer file and the value of 1 or 3 as nstatus. This status value needs to be 1 if the customer is found in the following (select custno from arship where dContract_Exp is null) and 3 if it is not.

select custno, iif(custno in (  select custno from arship where dContract_Exp is null ), 1, 3) as nstatus from dbo.customer

TIA
Jeff