The Customers relation scheme attributes are:

* Customer I.D., an arbitrary number or other unique identifier that we specify.
* Customer first name, a person's first name.
* Customer last name, a person's last name.
* Customer phone, a valid telephone number.
* Customer street, a street address.
* Customer zip code, a zip code designated by the United States Postal Service

The primary key attribute of the Customers relation is the Customer I.D.; 
the attributes first name, last name, and phone are a candidate key.

The Orders relation scheme attributes are:

* Customer I.D., foreign key from Customers.
* Order date, a calendar date possibly with the clock time.
* Sold by, the first name of the sales person taking the order.

The primary key attributes of the Orders relation are the foreign key
Customer I.D. plus the order date.

Return to [[Keys#Revising the relation scheme]]


''Other views of this diagram:'' 
* Large image: [[:Image:Keys-custorderscheme2-lg.gif]]
* Text: [[Customer-order relation scheme, revised, data dictionary]]