Chapter 6, Problem 21E

Explanation of Solution

a.

Extended ER diagram after adding Blu-ray discs and downable video:

Explanation:

In the above ER diagram, the two entities “video”, and “blue_ray_disc” are added to the ER diagram given in the Figure 6.30.

• The “video” entity contains “name”, and “price” attributes. Here, “name” is a primary key...

Explanation of Solution

b.

Extended ER diagram using generalization:

Explanation:

• The common attributes of “book”, “video”...