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

How about this:

SELECT DEF.Rate, ACTUAL.Rate, COALESCE(ACTUAL.Rate, DEF.Rate) AS UseThisRate
FROM 
  (SELECT 0) DEF (Rate) -- This is your default rate
LEFT JOIN (
  select rate 
  from d_payment_index
  --WHERE 1=2   -- Uncomment this line to simulate a missing value

  --...HERE IF YOUR ACTUAL WHERE CLAUSE. Removed for testing purposes...
  --where fy = 2007
  -- and payment_year = 2008
  --  and program_id = 18
) ACTUAL (Rate) ON 1=1

Results

Valid Rate Exists

Rate        Rate        UseThisRate
----------- ----------- -----------
0           1           1

Default Rate Used

Rate        Rate        UseThisRate
----------- ----------- -----------
0           NULL        0

Test DDL

CREATE TABLE d_payment_index (rate int NOT NULL)
INSERT INTO d_payment_index VALUES (1)