"Gill, Jerry T." <[EMAIL PROTECTED]> writes:
> Just an interesting side note here, this behavior is identical to DB2. I am
> not sure if that makes it correct or not, but here is an example.
> [EMAIL PROTECTED] gill]$ db2 "select 2 as id, max(apn3) from phoenix.client
> where 2 =1"
> ID 2
> ----------- ------
> 2 -
> 1 record(s) selected.
In the WHERE case I think there's no question that the above is correct:
WHERE is defined to filter rows before application of aggregates, so
zero rows arrive at the MAX aggregate, and that means it produces a
NULL.
But HAVING is supposed to filter after aggregation, so I think probably
there should be no row out in that case.
What does DB2 do when you say HAVING 2 = 1?
regards, tom lane
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
