CHAPTER 6
Database Design and
the E-R Model
Solutions to Practice Exercises
6.1 See Figure 6.1
6.2 See Figure 6.2.
In the answer given here, the main entity sets are student, course, course
offering,
and instructor. The entity set course
offering is a weak entity set dependent on
course. The assumptions made are :
a. A class meets only at one particular place and time. This
E-R diagram cannot
model a class meeting at different places at different times.
b. There is no guarantee that the database does not have two classes meeting
at the same place and time.
person owns
car
participated
accident
address
damage
_
amount
model
year
license
name
report
_
number
date
location
driver
_
id
driver
Figure 6.1 E-R diagram for a car insurance company.
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