PL/pgSQL function overloading

create table new_book
(
id serial,
title text,
author text
);

select * from new_book

--function untuk mengisi table new_book (ADD)
create or replace function ins_book(p_title varchar, p_author text)
returns integer as
$$
insert into new_book(title, author) values ($1,$2)
returning id;
$$
language 'sql' volatile;

select ins_book ('Qowaid Arba', 'Darul Haq') as book_id;
select ins_book ('Aqua', 'Rahad') as new_id;

--function untuk mengUpdate new_book (UPDATE)
create or replace function upd_book(log_id integer, p_title text, p_author text)
returns void as
$$
update new_book
set title = $2, author = $3 where id = $1;
$$
language 'sql' volatile;

select upd_book(4, 'Aqua', 'Imam');

--READ
create or replace function red_book(p_title varchar)
returns table (id int, title text, author text) as
$$
select id, title, author from new_book
where title like $1;
$$
language 'sql' stable;

select * from red_book ('sirah nabawi');

--OUT
create or replace function red_books_out (p_title varchar, out p_id int, out title text, out p_author text)
returns setof record as
$$
select * from new_book
where title like $1;
$$
language 'sql' stable;

select * from red_books_out ('Aqua');

--using composite type

create or replace function red_book_com(p_title text)
returns setof new_book as
$$
select * from new_book
where title like $1;
$$
language 'sql' stable;

select * from red_book_com ('Aqua');

--writing
create or replace function red_book_psql()
returns table (id int, title text, author text)as
$$
begin
    return query select * from new_book;
end;
$$
language 'plpgsql' stable;

select * from red_book_psql();

--trigger function

create or replace function f_trig_books() returns trigger as
$$
begin
new.title := upper(new.title);
return new;
end;
$$
language plpgsql volatile;

create trigger trigger_books
before insert or update of title, author
on new_book
for each row
execute procedure f_trig_books();

select ins_book('bahasa arab', 'darul haq') as new_id;

drop function ins_book