Demonstrating a FK does not require a PK in SQL

foreign_key.sql

begin transaction;

create table Location
(
    Id int primary key,
    City varchar(255),
    [State] char(2),
    Zip char(5) unique,
);

create table Address
(
    Id int primary key,
    [Name] varchar(255),
    Street varchar(255),
    Zip char(5) references location(Zip),
);

insert into [Location] 
(Id, City, [State], Zip) 
values 
(1, 'New York', 'NY', '10001'),
(2, 'Los Angeles', 'CA', '90001'),
(3, 'Chicago', 'IL', '60007'),
(4, 'Houston', 'TX', '77001'),
(5, 'Phoenix', 'AZ', '85001');

insert into [Address]
(Id, [Name], Street, Zip)
values
(1, 'Home', '123 Main St', '10001'),
(2, 'Work', '456 Elm St', '90001'),
(3, 'School', '789 Oak St', '60007'),
(4, 'Gym', '101 Pine St', '77001'),
(5, 'Park', '202 Cedar St', '85001');

SELECT Street, City, [State], Address.Zip
FROM Address
JOIN Location ON Address.Zip = Location.Zip;

rollback;