Re: Stored procedures and "pseudo" fields..

В Втр, 20.07.2004, в 15:57, Tomasz Myrta пишет:
> On 2004-07-20 15:34, Użytkownik Lars Erik Thorsplass napisał:
> > 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.
> >
> > Kinda like this:
> >
> > SELECT *, acl_check( objects.obid, <user_id> ) AS mode FROM objects
> > WHERE mode > 0;
> >
> > This gives me a: ERROR:  column "mode" does not exist
>
> You can't access column output alias in where clause. Instead you have
> to use your function twice:
>
> 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.

--
Markus Bertheau <twanger@bluetwanger.de>