How to set a default row for a query that returns no rows?

Question

I need to know how to return a default row if no rows exist in a table. What would be the best way to do this? I\'m only returning a single column from this particular table

Answer 1

I figured it out, and it should also work for other systems too. It's a variation of WW's answer.

select rate 
from d_payment_index
where fy = 2007
  and payment_year = 2008
  and program_id = 18
union
select 0 as rate 
from d_payment_index 
where not exists( select rate 
                  from d_payment_index
                  where fy = 2007
                    and payment_year = 2008
                    and program_id = 18 )