Tagged Questions
12
votes
3answers
761 views
Why does ANSI SQL define SUM(no rows) as NULL?
The ANSI SQL standard defines (chapter 6.5, set function specification) the following behaviour for aggregate functions on empty result sets:
COUNT(...) = 0
AVG(...) = NULL
MIN(...) = NULL
MAX(...) = ...
35
votes
4answers
5k views
What is the difference between select count(*) and select count(any_non_null_column)?
I seem to remember that (on Oracle) there is a difference between uttering select count(*) from any_table and select count(any_non_null_column) from any_table.
What are the differences between these ...
