Message-ID: <438477C3.6080208@archonet.com>
Date: Wed, 23 Nov 2005 14:08:03 +0000
From: Richard Huxton <dev@archonet.com>
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To: lucas@presserv.org
Cc: pgsql-sql@postgresql.org
Subject: Re: Default on update
References: <20051123084353.8ga6nrpx43gg8408@www.presserv.org>
	<43845F23.60204@archonet.com>
	<20051123104134.3be3vpyxlc00kko4@www.presserv.org>
	<20051123105626.fon1t82f0ctcgogw@www.presserv.org>
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lucas@presserv.org wrote:
>>> I would want to replace "bv" values with FALSE when insert/update 
>>> NULL value for
>>> this field.
>>
>> You could do this by having the application insert to a view with a 
>> rule that replaces null bv values before redirecting to the base table.
> 
> Is more functional to create a Rule instead of a trigger?

It's different - you can think of a rule as a kind of macro, rewriting 
the query the application provides. Make sure you read the manuals 
carefully to be sure you understand how they work though.

>>> Or need I create a TRIGGER that check it and replace the itens???
>>> CREATE or REPLACE function TG_table1_check RETURNS trigger as '
>>>  BEGIN
>>>   IF nullvalue(NEW.bv) THEN
>>
>>
>> IF NEW.bv IS NULL THEN
>>
> What is the difference between nullvalue() and IS NULL???

"IS NULL" is a standard SQL expression.

-- 
   Richard Huxton
   Archonet Ltd