Tagged Questions
11
votes
3answers
264 views
What is the correct result for this query?
I came across this puzzle in the comments here
CREATE TABLE r (b INT);
SELECT 1 FROM r HAVING 1=1;
SQL Server and PostgreSQL return 1 row.
MySQL and Oracle return zero rows.
Which is correct? ...
12
votes
3answers
767 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(...) = ...
