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Trigger Update not working if starts null

Posted on 2014-09-30
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Last Modified: 2014-10-17
If got a simple trigger which is to update a log table (which I unfortunately need), however if the value of `phoneNumber` is its default of Null, when I update it like:-
UPDATE `contract` SET `phoneNumber` = '44464' WHERE `contract`.`priID` = 8;

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I dont get a line in the logger, however if I execute again differently so the so OLD.`phoneNumber` isnt null then trigger fires fine and runs the insert command.

My trigger code is:-
Begin
IF OLD.`phoneNumber` <> NEW.`phoneNumber` THEN
             INSERT INTO `mobilephones`.`_logger` (`dateTime`, `connectionID`, `table`, `priID`, `feild`, `newValue`,`action`) VALUES (NOW(), CONNECTION_ID(), 'contract', NEW.`priID`, 'phoneNumber', NEW.`phoneNumber`, 'Update');
END IF; 
End

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Any ideas what Im doing wrong?
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Question by:tonelm54
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Accepted Solution

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Julian Hansen earned 2000 total points
ID: 40353211
The article below might shed some light

http://coldfusionbeyond.com/post.cfm/mysql-trigger-flakiness-and-null-in-comparisons

Basically saying that comparing null to null gives null and not 1 (equal).

Not sure if the suggested work around can help but it might give some insight.
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