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

One approach for Oracle:

SELECT val
FROM myTable
UNION ALL
SELECT 'DEFAULT'
FROM dual
WHERE NOT EXISTS (SELECT * FROM myTable)

Or alternatively in Oracle:

SELECT NVL(MIN(val), 'DEFAULT')
FROM myTable

Or alternatively in SqlServer:

SELECT ISNULL(MIN(val), 'DEFAULT')
FROM myTable

These use the fact that MIN() returns NULL when there are no rows.

If your base query is expected to return only one row, then you could use this trick:

select NVL( MIN(rate), 0 ) AS rate 
from d_payment_index
where fy = 2007
  and payment_year = 2008
  and program_id = 18

(Oracle code, not sure if NVL is the right function for SQL Server.)

Related