Re: How can I get one OLD.* field in a dynamic query inside a trigger function ?

Le 24/10/09 06:46, Pavel Stehule a écrit :
> 2009/10/24 Bruno Baguette <bruno(dot)baguette(at)gmail(dot)com>:
>> Hello !
>>
>> I'm trying to write a little trigger function with variable arguments
>> quantity (at least one, but can be 2,3,4 arguments).
>> Theses arguments are fields name, so only varchar variable.
>>
>> Since it is a dynamic query, I use the EXECUTE statement as explained on
>> <http://www.postgresql.org/docs/8.3/interactive/plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN>
>>
>> CREATE OR REPLACE FUNCTION delete_acl_trigger() RETURNS trigger AS
>> $delete_acl_trigger$
>> DECLARE
>> BEGIN
>> FOR i IN 0 .. TG_NARGS LOOP
>> EXECUTE 'SELECT delete_acl(OLD.' || TG_ARGV[i] || ');';
>> END LOOP;
>> RETURN OLD;
>> END;
>> $delete_acl_trigger$ LANGUAGE plpgsql;
>>
>> But, when the trigger is triggered, I receive this error message :
>> "Query failed: ERROR: OLD used in query that is not in a rule"
>>
>> How can I get the value of the OLD.' || TG_ARGV[i] field ?
>
> OLD is variable only in PLpgSQL procedure, - outside doesn't exists.
> If you have a 8.4, you can use USING clause
>
> EXPLAIN 'SELECT $1.' || TG_ARGV[i] INTO somevar USING OLD;
>
> http://www.postgresql.org/docs/8.4/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN

Hello Pavel,

Thanks for your answer !

Unfortunately, I'm running PostgreSQL 8.3.7 (PostgreSQL 8.3.7 on
i586-mandriva-linux-gnu, compiled by GCC i586-mandriva-linux-gnu-gcc
(GCC) 4.2.3 (4.2.3-6mnb1)).

Since 8.4.1 is not available for Mandriva 2009.1, I can only have this
PostgreSQL version. (I don't have root access on that server).

Is there another way, usable in PostgreSQL 8.3.7, to solve my problem ?

Many thanks in advance !

Kind Regards,

--
Bruno Baguette - bruno(dot)baguette(at)gmail(dot)com