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.

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 Loans relation scheme attributes are:

• Customer I.D., foreign key from Customers.
• Call number, foreign key from Books-on-the-Shelf.
• Copy number, foreign key from Books-on-the-Shelf.
• Date and time out, a calendar date with the clock time.
• Scanner I.D., an arbitrary number that identifies that piece of equipment.
• Date due, a calendar date.
• Date returned, a calendar date.

The primary key attributes of the Loans relation are the foreign keys call number and copy number plus the date and time out, a discriminator attribute. The Date and time out and the scanner I.D. attributes form an additional candidate key.

The Books-on-the-shelf relation scheme attributes are:

• Call number, foreign key from Catalog Entries.
• Copy number, an integer.

The primary key attributes of the Books-on-the-shelf relation are the foreign key from Catalog Entries plus the copy number.

The Catalog Entries relation scheme attributes are:

• Call number, an external key assigned by the Library of Congress.
• Title, the title of the book.
• Publication date, a calendar year.
• Publisher, a company name.
• ISBN, a designation supplied by the publisher.

The primary key attribute of the Catalog Entries relation is the call number; the attributes title and publication date are a candidate key, as is the ISBN.

Return to main page