create table usr(id integer primary key, name varchar(100), cityid integer);
create table city (id integer primary key, name varchar(100));

insert into usr values (1, 'John', 1);
insert into usr values (2, 'Marry', 1);
insert into usr values (3, 'Eva', 2);
insert into usr values (4, 'Zby', 3);
insert into city values (1, 'New York');
insert into city values (2, 'London');
insert into city values (3, 'Warsaw');