Re: Plpgsql function with unknown number of args

In article <1806D1F73FCB7F439F2C842EE0627B1801C32853(at)usa0300ms01(dot)na(dot)xerox(dot)net>,
"Relyea, Mike" <Mike(dot)Relyea(at)xerox(dot)com> writes:

> I need to create my very first function. I'm using 8.0.2 and I need a
> function that I can call (from my client app) with an unknown number of
> criteria for a select query. The function will then return the results
> of the query. In my mind, it would go something like what I've outlined
> below. I realize that there are syntax mistakes etc, but this is just
> an example:

> CREATE TABLE mytable (
> a INTEGER UNIQUE PRIMARY KEY,
> b VARCHAR(100) NOT NULL,
> );

> CREATE FUNCTION myfunc(criteria) RETURNS ???? AS $$

> BEGIN

> BEGIN
> FOREACH crit IN criteria
> critsql := "b = 'crit' OR "
> NEXT crit
> END;

> PERFORM "SELECT a, b FROM mytable WHERE (" critsql ");"

> END;
> $$ LANGUAGE plpgsql;

> Select * from myfunc(1, 2, 3, 4) would then equate to SELECT a, b FROM
> mytable WHERE (b = '1' OR b = '2' OR b = '3' OR b = '4');

> Select * from myfunc(9, 21) would equate to SELECT a, b FROM mytable
> WHERE (b = '9' OR b = '21');

> My question is how do I do that? I've looked through the docs and can't
> find what I'm looking for. I'm assuming this is possible because it's a
> relatively simple task.

You can't have a variable number of args, but since all args have the
same type you can use an array. The return type is a set of mytable
rows; thus myfunc becomes something like

CREATE FUNCTION myfunc (TEXT[]) RETURNS SETOF mytable AS $$
SELECT *
FROM mytable
WHERE b = ANY ($1)
$$ LANGUAGE sql;

This function can be called like that:

SELECT *
FROM myfunc (ARRAY ['1', '2', '3', '4']);

SELECT *
FROM myfunc (ARRAY ['9', '21']);