Re: Using null or not null in function arguments

On Jan 23, 2009, at 10:11 , Igor Katson wrote:

> That one is awesome, thanks, I completely forgot about CASE
> statement. The search func now looks as follows, and works perfectly:
>
> CREATE OR REPLACE FUNCTION isocial_user_func.search_users
> (i_city_id int, i_edu_id int, i_firstname text, i_lastname text,
> limit_ int, offset_ int) RETURNS SETOF isocial_user.user AS $$
> DECLARE
> rec isocial_user.user;
> BEGIN
> FOR rec IN SELECT * FROM isocial_user.user
> WHERE
> CASE
> WHEN i_city_id IS NULL THEN TRUE
> ELSE city_id = i_city_id
> END AND
> CASE
> WHEN i_edu_id IS NULL THEN TRUE
> ELSE edu_id = i_edu_id
> END AND
> CASE
> WHEN i_firstname IS NULL THEN TRUE
> ELSE upper(firstname) ~ upper(i_firstname)
> END AND
> CASE
> WHEN i_lastname IS NULL THEN TRUE
> ELSE upper(lastname) ~ upper(i_lastname)
> END
> LIMIT limit_
> OFFSET offset_
> LOOP
> RETURN NEXT rec;
> END LOOP;
> RETURN;
> END;
> $$ language plpgsql;

Here's an alternate formulation that eliminates the CASE statements
which I find hard to read:

CREATE OR REPLACE FUNCTION isocial_user_func.search_users
(i_city_id int, i_edu_id int, i_firstname text, i_lastname text,
limit_ int, offset_ int) RETURNS SETOF isocial_user.user AS $$
DECLARE
rec isocial_user.user;
BEGIN
FOR rec IN
SELECT *
FROM isocial_user.user
WHERE (i_city_id IS NULL OR city_id = i_city_id)
AND (i_edu_id IS NULL OR edu_id = i_edu_id)
AND (i_firstname IS NULL OR upper(firstname) ~
upper(i_firstname))
AND (i_lastname IS NULL OR upper(lastname) ~
upper(i_lastname))
LIMIT limit_
OFFSET offset_
LOOP
RETURN NEXT rec;
END LOOP;
RETURN;
END;
$$ language plpgsql;

And you really don't even need to use PL/pgSQL: an SQL function would
work just as well.

CREATE OR REPLACE FUNCTION
isocial_user_func.search_users (i_city_id int, i_edu_id int,
i_firstname text, i_lastname text,
limit_ int, offset_ int,
<OUT columns>)
RETURNS SETOF RECORD
LANGUAGE SQL AS $$
SELECT *
FROM isocial_user.user
WHERE ($1 IS NULL OR city_id = i_city_id)
AND ($2 IS NULL OR edu_id = i_edu_id)
AND ($3 IS NULL OR upper(firstname) ~ upper(i_firstname))
AND ($4 IS NULL OR upper(lastname) ~ upper(i_lastname))
LIMIT $5
OFFSET $6
$$;

Michael Glaesemann
grzm seespotcode net