Postgres 14

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drop table if exists sales cascade;
create table sales(id serial primary key, website text, content text);
insert into sales values
    (default, 'Google', 'content1'),
    (default, 'Yahoo', 'content2'),
    (default, 'Google', 'content3'),
    (default, 'Yahoo', 'content4'),
    (default, 'Google', 'content5');
5 rows affected

drop function if exists select_from_sales(arg text);
create or replace function select_from_sales(arg text)
returns setof sales language sql as $$
    select * from sales where website = arg
$$;

select *
from select_from_sales('Google')


id
website
content


1
Google
content1

3
Google
content3

5
Google
content5


alter table sales add extra text default 'extra';

select *
from select_from_sales('Yahoo')


id
website
content
extra


2
Yahoo
content2
extra

4
Yahoo
content4
extra


alter table sales drop extra;

select *
from select_from_sales('Yahoo')


id
website
content


2
Yahoo
content2

4
Yahoo
content4