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From:Michael Widenius Date:October 14 1999 2:01am
Subject:Is this right?
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>>>>> "Michael" == Michael Farr <farrm@stripped>
> writes:

Michael> The only difference in the last two queries is the ISNULL(p.patientId) =>
> ISNULL(d.patientId) 
mysql> SELECT p.patientId FROM Patient p LEFT JOIN DentalScheme d ON p.patientId =
> d.patientId ;                          
Michael> +-----------+
Michael> | patientId |
Michael> +-----------+
Michael> |         1 |
Michael> |         2 |
Michael> |         3 |
Michael> |         4 |
Michael> +-----------+
Michael> 4 rows in set (0.00 sec)

Michael> I didn't think p.patientId should be NULL here
mysql> SELECT p.patientId FROM Patient p LEFT JOIN DentalScheme d ON p.patientId =
> d.patientId WHERE ISNULL(p.patientId) ;
Michael> +-----------+
Michael> | patientId |
Michael> +-----------+
Michael> |         4 |
Michael> +-----------+
Michael> 1 row in set (0.00 sec)

mysql> SELECT p.patientId FROM Patient p LEFT JOIN DentalScheme d ON p.patientId =
> d.patientId WHERE ISNULL(d.patientId) ; 
Michael> +-----------+
Michael> | patientId |
Michael> +-----------+
Michael> |         4 |
Michael> +-----------+
Michael> 1 row in set (0.00 sec)	

Hi!

What is your MySQL version ?   (Please repost with mysqlbug).

Can you do a full test case of this that we can test?

Regards,
Monty
Thread
Is this right?Michael Farr13 Oct
  • Is this right?Michael Widenius14 Oct
    • Re: Is this right?Michael Farr14 Oct