Data Type for select in plpgsql function and access its fields - postgresql

Question

I have the following tables in a Postgres 9.5 database:
product
Column | Type | Modifiers
----------------+-----------------------------+-----------------------------------------------------
id | integer | not null default nextval('product_id_seq'::regclass)
name | character varying(100) |
number_of_items | integer |
created_at | timestamp without time zone | default now()
updated_at | timestamp without time zone | default now()
total_number | integer |
provider_id | integer |
Indexes:
"pk_product" PRIMARY KEY, btree (id)
Foreign-key constraints:
"fk_product_provider" FOREIGN KEY (provider_id) REFERENCES provider(id)
And we also have
provider
Column | Typ | Modifiers
-------------+------------------------+------------------------------
id | integer | not null default nextval('property_id_seq'::regclass)
name | text |
description | text |
created_at | timestamp without time zone | default now()
updated_at | timestamp without time zone | default now()
Indexes:
"pk_provider" PRIMARY KEY, btree (id)
I am implelemtnig a plpgsql function which is supposed to find some specific products of a provider and loop through them
products = select u_id, number_of_items from product
where provider_id = p_id and total_number > limit;
loop
//here I need to loop through the products
end loop;
Question
what kind of data type should I declare for the products variables in order to store queried products into it? and also how should I have later on access to its columns like id or number_of_items?

Answer 1

In PostgreSQL, creating table also defines a composite data type with the same name as the table.
You can either use a variable of that type:
DECLARE
p product;
BEGIN
FOR p IN SELECT product FROM product WHERE ...
LOOP
[do something with "p.id" and "p.val"]
END LOOP;
END;
Or you can use several variables for the individual fields you need (probably better):
DECLARE
v_id integer;
v_val text;
BEGIN
FOR v_id, v_val IN SELECT id, val FROM product WHERE ...
LOOP
[do something with "v_id" and "v_val"]
END LOOP;
END;