SELECT SUM returns a row when there are no records

Question

Hi,

I'm finding some problems with a query that returns the sum of a field from a table for all the records that meet certain conditions. I expected to receive a "No records found' when there were no records, but instead I'm receiving a null result.

SQL> SELECT * FROM DUAL WHERE 1=2;

no rows selected
SQL> SELECT SUM(dummy) FROM DUAL WHERE 1=2;

SUM(DUMMY)
----------


SQL>

Is there any way to not receive any record in that case?

Answer 1

How about this:

select my_sum
from
(SELECT SUM(dummy) as my_sum FROM DUAL WHERE 1=2)
where
my_sum is not null

Answer 2

You can filter out the null results with having

SELECT SUM(dummy) FROM DUAL WHERE 1=2 HAVING SUM(dummy) IS NOT NULL

Answer 3

No - this is the behavior by design of the RDBMS in use here, Which, to me atleast, makes sense, as you are looking for a sum and not raw data

Answer 4

"I expected to receive a "No records found' when there were no records, but instead I'm receiving a null result."

Then do

SELECT SUM(dummy) FROM DUAL WHERE 1=2 HAVING COUNT(*) > 0

That is, specify that you only want to return a summary where there were rows that were considered.

SELECT SUM(dummy) FROM DUAL WHERE 1=2 HAVING SUM(dummy) IS NOT NULL

is similar, but the COUNT(*) would return a summary row if there were only rows for which dummy was null, while the latter would not.