drop table if exists product;
drop table if exists region;
drop table if exists price;

create table product(id int, name varchar(99));
create table region(id int, name varchar(99));
create table price(productId int, regionId int, price decimal(9, 2));

insert into product values(1, 'Crab');
insert into product values(2, 'Crayfish');
insert into region values(1, 'Kiev');
insert into region values(2, 'Kharkov');
insert into region values(3, 'Lvov');
insert into price values(1, 1, 100);
insert into price values(1, 2, 100);
insert into price values(1, 3, 200);
insert into price values(2, 1, 200);
insert into price values(2, 2, 100);
insert into price values(2, 3, 100);

select pt.name, rg.name, pr.price
from price pr
left join product pt on pt.id = pr.productId
left join region rg on rg.id = pr.regionId
group by pt.name having min(pr.price)