[Cialug] mysql triggers -- figured them out

[Kevin C. Smith]

Yep. And I needed it to always fire.

> Triggers always fire, but if you put these kinds of rules in a Stored
> Procedure, they only fire when you call the SP. Example: if another web
> page inserts a record or does an update without using the SP (say
> another developer adds a page...) then your SP rules don't get applied.
>
> Using the Trigger, even if you just enter a record using phpMyAdmin, or
> the mysql console, the rules will be enforced.
>
> -dc
>
> carl-olsen at mchsi.com wrote:
>> I thought about checking into it for you, but I haven't really figured
>> out a reason to use triggers yet.  I seem to be able to do the same
>> things using stored procedures, such as checking another table before
>> doing an insert, update or delete to see if a certain condition is true
>> or false.  I like being able to do this stuff inside the database
>> instead of making a bunch of diffent PHP queries.  It seems to take less
>> typing to do it all in a stored procedure.  I'm glad you figured it out.
>>  I bought a good book, if you're interested, "MySQL Store Procedure
>> Programming" by O'Reilly, ISBN 0-596-10089-2. It also has a chapter on
>> triggers.
>>
>> Carl Olsen
>> http://www.carl-olsen.com/
>>
>>
>> -------------- Original message from "Kevin C. Smith"
>> <kevin at linuxsmith.com>: --------------
>>
>>
>>
>>>Since I got no response I thought some might be interested in the
>>> solution.
>>>After reading the docs it turns out to be fairly simple. Yes, I didn't
>>>read the docs before; I was trying speed it up by getting pointed to
>>>the TIMEDIFF function. To get the time difference of two fields using a
>>>trigger.
>>>
>>>CREATE TRIGGER trigger_time BEFORE INSERT ON time_table FOR EACH ROW SET
>>>NEW.time_diff = TIMEDIFF(NEW.end_time, NEW.begin_time);
>>>
>>>Of course an ON UPDATE trigger is also needed.
>>>
>>>
>>>--
>>>Kevin C. Smith
>>>
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>>>
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-- 
Kevin C. Smith