Subject: Re: Stored procedures and "pseudo" fields..
From: Markus Bertheau <twanger@bluetwanger.de>
To: Tomasz Myrta <jasiek@klaster.net>
Cc: Lars Erik Thorsplass <thorsplass@gmail.com>,
	pgsql-sql@postgresql.org
In-Reply-To: <40FD24D1.1090005@klaster.net>
References: <7eeb33a040720034319e036c6@mail.gmail.com>
	<7eeb33a04072006342b5d35a0@mail.gmail.com>
	<40FD24D1.1090005@klaster.net>
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Date: Tue, 20 Jul 2004 16:11:16 +0200
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=D0=92 =D0=92=D1=82=D1=80, 20.07.2004, =D0=B2 15:57, Tomasz Myrta =D0=BF=D0=
=B8=D1=88=D0=B5=D1=82:
> On 2004-07-20 15:34, U=C5=BCytkownik Lars Erik Thorsplass napisa=C5=82:
> > My stored procedure "acl_check()" takes two integers as parameters.
> > Param1 is the object id to check acl on, Param 2 is the object id of
> > the user currently using the system. The procedure returns a positive
> > number (1 or 3 ) if you have some kind of access to the object. As one
> > might understand I want the returned value from the acl_check()
> > procedure to be a part of the result set.
> >=20
> > Kinda like this:
> >=20
> > SELECT *, acl_check( objects.obid, <user_id> ) AS mode FROM objects
> > WHERE mode > 0;
> >=20
> > This gives me a: ERROR:  column "mode" does not exist
>=20
> You can't access column output alias in where clause. Instead you have=20
> to use your function twice:
>=20
> SELECT *, acl_check( objects.obid, <user_id> ) AS mode FROM objects
> WHERE acl_check( objects.obid, <user_id> ) > 0;

and if you properly marked the function STABLE and I am not mistaken,
then PostgreSQL is smart enough to execute the function only once per
row.

--=20
Markus Bertheau <twanger@bluetwanger.de>