Re: Strange query behavior

[gerald_clark]

Linus Nikander wrote:

Whilst trying to figure out why one of my queries wasn't working I ran into
the following phenomenon which I'd be grateful if someone could explain.
(I'm running mySQL 4.0.17 on a win2003 server, querying using the 0.9.4
mysql control center)
The following query returns the expected result
SELECT
   distinct(PO.error_type) AS error_type,
   COUNT(PO.error_type) AS occurrence
FROM
   problematic_odds AS PO
WHERE NOT
   (PO.error_type = 100)
GROUP BY
   PO.error_type
it returns 1008 ,212 for error_type and occurrence respectively.
When I change the query to
SELECT
   distinct(PO.error_type) AS error_type,
   COUNT(PO.error_type) AS occurrence
FROM
   problematic_odds AS PO,
   active_odds AS AO
This cartesian product will be empty if active_odds is empty.

WHERE NOT
   (PO.error_type = 100)
GROUP BY PO.error_type
the query executes BUT doesn't return anything at all. I can't quite figure
out why. The only difference between the two queries is that the second one
has "active_odds AS AO"  added to the FROM clause. Even though I don't use
AO at all in the query the results still differ. Anyone have an explanation
? Having a superflous table in the WHERE clause shouldn't affect the query
outcome should it ?
//Linus Nikander - [EMAIL PROTECTED]





 



--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe:    http://lists.mysql.com/[EMAIL PROTECTED]