Thread: Triggers | rules for column updates

Hi!

I want to prevent any changes to a tuple if a field of the tuple has a
certain value. Let's say I have a table with column col_1, col_2, col_3.
I want to create something that will prevent updating col_2 and col_3 if
and only if col_1 is say "1".
Can I use a rule to do that. Can I somehow detect in a trigger function
the name of the columns that are updated? If I could do that, it would
be easy to create a trigger that would do the job.
I am also opened to other kind of solutions that you might know of.
Any help will be appreciated ;)

--
Szentpáli János

am  Mon, dem 03.03.2008, um 15:47:58 +0200 mailte Szentpali Janos folgendes:
> Hi!
>
> I want to prevent any changes to a tuple if a field of the tuple has a
> certain value. Let's say I have a table with column col_1, col_2, col_3.
> I want to create something that will prevent updating col_2 and col_3 if
> and only if col_1 is say "1".
> Can I use a rule to do that. Can I somehow detect in a trigger function

I think, a RULE isn't the solution, but you can use a BEFORE UPDATE -
Trigger to check if OLD.col_1 = 1 and, in this case, RAISE an error.



Andreas
--
Andreas Kretschmer
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