CREATE FUNCTION `udf_users_photos_count` (username VARCHAR(30))
RETURNS INTEGER
BEGIN
RETURN (select count(p.id) from photos as p
inner join users_photos as up
on p.id = up.photo_id
inner join users as u
on u.id = up.user_id
where u.username = username);

END

CREATE PROCEDURE `udp_modify_user` (address VARCHAR(30), town VARCHAR(30))
BEGIN
update users as u
set u.age =
case
when (select user_id from addresses as a
where a.address = address and a.town = town
) = u.id then u.age = u.age + 10
else age
end;
select u.username, u.email, u.gender, u.age, u.job_title from users as u
inner join addresses as a
on a.user_id = u.id
where a.address = address and a.town = town;
END