How to declare function that return set of data from tables? for example :
CREATE TYPE "public"."cst_test" AS (
"code" VARCHAR(10),
"name" VARCHAR(50),
"quantity" NUMERIC(10,2) );
CREATE OR REPLACE FUNCTION public."sf_test"(id_code VARCHAR)
RETURNS SETOF "public"."cst_test" AS
$body$
SELECT
t1.code,
t1.name,
t2.quantity
FROM "public"."test_1" t1
INNER JOIN "public"."test_2" t2 ON t1.id_test1 = t2.id_test1
WHERE t1.code = $1
$body$
LANGUAGE 'sql' ;
It's STABLE, IMMUTABLE OR VOLATILE?