Q$02)$ Consider the E$-$R diagram in Figure $7\mathrm{.}29,$ which models an online bookstore.

a$.$ List the entity sets and their primary keys.

b$.$ Suppose the bookstore adds Blu$-$ray disos and downloadable video to its collection. The same item may be present in one or both formats, with differing prices. Extend the E$-$R diagram to model this addition, ignoring the effect on shopping baskets.

c$.$ Now extend the E$-$R diagram, using generalization, to model the case where a shopping basket may contain any combination of books, Blu$-$ray discs, or downloadable video.

$\backslash$table$[[$author$],[\backslash$table$[[$name$],[$address$],[$URL$]]]]$

customer

written$\_$by

email

name address phone

book

ISBN

title

year

price

number

published$\_$by

slopping$\_$basket

lnsket$\_$id

contains

basket$\_$of

number