drop table sales cascade;
drop table item cascade;
drop table store cascade;

create table store (
	code integer primary key,
	name text not null
);
insert into store values(1, '新宿店');
insert into store values(2, '渋谷店');
insert into store values(3, '池袋店');

create table item (
	code integer primary key,
	name text not null,
	price integer not null check(price > 0)
);
insert into item values(1, 'コカコーラ', 95);
insert into item values(2, 'Ｍサイダー', 88);
insert into item values(3, 'ＣＣレモン', 90);

create table sales (
	s_code integer references store(code),
	i_code integer references item(code),
	num integer
);
insert into sales values(1, 1, 15);
insert into sales values(1, 2, 8);
insert into sales values(2, 2, 11);
insert into sales values(2, 3, 7);
insert into sales values(3, 1, 10);
insert into sales values(3, 3, 9);