Re: Using null or not null in function arguments

Michael Glaesemann wrote:
>
> 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
>
>
>
Thank you, Michael, that one looks prettier.
Sam, I'm not sure if this is correct to do that, as you I don't want to
remember what will happen, if you use NULL = NULL or upper(NULL) etc.:

WHERE
COALESCE(city_id = i_city_id, TRUE) AND
COALESCE(edu_id = i_edu_id, TRUE) AND
COALESCE(upper(firstname) ~ upper(i_firstname), TRUE) AND
COALESCE(upper(lastname) ~ upper(i_lastname), TRUE)