Return ResultSet in pgsql function - postgresql

Question

I have the function below...
CREATE OR REPLACE FUNCTION class_listing(var_sem integer, var_sy character) RETURNS SETOF RECORD AS
DECLARE
current_offering record;
BEGIN
SELECT subcode, offerno INTO current_offering FROM offering WHERE SY=var_sem AND SEM=var_sy;
END;
How to return current_offering as resultset?

Answer 1

You can use a SQL or PLpgSQL functions. Using anonymous records as returning type is not practical (mainly it is not friendly, when you write queries). Use RETURNS TABLE or OUT parameters instead.
CREATE OR REPLACE FUNCTION class_listing(var_sem integer, var_sy varchar)
RETURNS TABLE (subcode varchar, offerno int) AS $$
BEGIN
RETURN QUERY SELECT o.subcode, o.offerno
FROM offering
WHERE SY=var_sem AND SEM=var_sy;
END;
$$ LANGUAGE plpgsql;
or SQL language
CREATE OR REPLACE FUNCTION class_listing(var_sem integer, var_sy varchar)
RETURNS TABLE (subcode varchar, offerno int) AS $$
SELECT o.subcode, o.offerno
FROM offering
WHERE SY=$1 AND SEM=$2;
$$ LANGUAGE sql;
Attentions - query based functions works (with small exception) as optimizer barrier. So be careful when you use it in complex queries.
For completeness - your example can be written as:
CREATE OR REPLACE FUNCTION class_listing(var_sem integer, var_sy varchar)
RETURNS SETOF RECORD AS $$
DECLARE current_offering record;
BEGIN
FOR current_offering IN
SELECT o.subcode, o.offerno
FROM offering
WHERE SY=var_sem AND SEM=var_sy;
LOOP
RETURN NEXT current_offering;
END LOOP;
RETURN;
END;
$$ LANGUAGE plpgsql;
But this form is deprecated now