QUESTION

 

The Motor Vehicle Branch administers driving tests and issues driver’s licenses. Any person who wants a driver’s license must first take a learner’s exam at any Motor Vehicle Branch in the province. If he/she fails the exam, he can take the exam again any time after a week of the failed exam date, at any branch. If he passes the exam, he is issued a license (type = learner’s) with a unique license number. The person may take his driver’s exam at any branch any time before the learner’s license expiry date (which is usually set at six months after the license issue date). If he passes the exam, the branch issues him a driver’s license.

 

Create an E-R diagram following these steps.

1. Find out the entities.

2. Find out the relationships among the entities.

3. Figure out attributes of the entities and (if any) of the relationships.

4. Figure out constraints between entities and relationships.

ANSWER

Entities and Attributes:

Driver: dssn, dname, daddress, dphone.

Branch: bid, bname, baddress, bphone.

License: lno, lclass, lexpiry.

Learner_license.

Driver_license.

Relationships:

relation

The “is a” relationship: Learner_license “is a” license, Driver_license “is a” license.

 

er

 

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