Re: Function with DEFAULT arguments

On Fri, Mar 12, 2010 at 05:28:57PM +0100, dario(dot)ber(at)libero(dot)it wrote:
> Hello,
>
> I'm trying to use the DEFAULT option to pass parameters to the arguments of a
> function.
> When I call that function, how can I change the default value of some
> arguments and leave as default the value of other arguments? In other words, is
> there a way to 'call' the arguments by their names so to specify which should
> have their default value changed?
>
> Here's a toy example, a function that takes three strings as arguments and
> concatenate them:
>
> CREATE FUNCTION test_default(string1 text default 'a', string2 text default
> 'b', string3 text default 'c') RETURNS text AS $$
> BEGIN
> RETURN string1 || string2 || string3;
> END;
> $$ language 'plpgsql';
>
> -- Only default args:
> SELECT test_default(); --> abc
>
> -- With custom values:
> SELECT test_default('X', 'Y', 'Z'); --> XYZ
>
> -- Now, how can I leave as default the 1st and 3rd argument (string1 and
> string3) and change only the second one (string2)? I would like to do something
> like:

You can't unless you're on PostgreSQL 9.0:
http://www.depesz.com/index.php/2009/11/17/waiting-for-8-5-named-function-arguments/

depesz

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