[sqlite] SUM and NULL values

[Will Leshner]

Say I have a column called 'b' in a table called 'test' and every  
field in 'b' has a NULL value. What is the expected behavior of the  
following query:

SELECT SUM(b) FROM TEST;
I guess I'm thinking I'll get back NULL. Instead I get 0 (or, in the  
3.2.5 code, 0.0).

On the other hand, the following query does return NULL:

SELECT AVG(b) FROM TEST;