[snip] Alan Nilsson wrote: > > On Oct 30, 2006, at 3:27 PM, Jay Blanchard wrote: > >> [snip] >> I am trying to find records where the value of a filed is NULL. I >> know that there are records that have null values but the result is >> always an empty set. >> >> eg: >> select test_id from tests where test_id=NULL >> >> always returns an empty set when there are in fact records that have >> a null value for test_id. Is there some trick to finding null valued >> records in MySQL? This same sql has always worked on any other dbms >> I have used. >> [/snip] >> >> Of course this will return an empty set because you have only selected >> the test_id, try this; >> >> SELECT * FROM tests WHERE test_id IS NULL > > Yes, that works, but I was also trying SELECT * instead of just the key > field (just a typo in the example). The problem was in the equal sign
> versus the 'IS' operator. Any reason why MySQL does not honor > <field>=NULL? Seems kind of odd. Sql standard says you use IS NULL. [/snip] And the reason for that is because nothing is actually equal to NULL. For a field to be equal to NULL it would actually have to contain NULL, in which case it would not be actually NULL. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
