The main relation of a motor vehicle registration bureau\'s relational database
ID: 3879880 • Letter: T
Question
The main relation of a motor vehicle registration bureau's relational database includes the following attributes:
The Vehicle Identification Number is a unique number assigned to the car when it is manufactured. The License Plate Number is, in effect, a unique number assigned to the car by the government when it is registered. The Owner Serial Number is a unique identifier of each owner. Each owner can own more than one vehicle. The other attributes are not unique.
What is/are the candidate key(s) of this relation? If there is more than one candidate key, choose one as the primary key and indicate which is/are the alternate key(s).
VIN License Plate Owner Serial # Manufacturer Model Year ColorExplanation / Answer
Candidate key(s) of a relation is the minimal set of attribute which can uniquely identify a tuple in a relation.
For the above relation, Vehicle Identification Number(VIN) is a unique number assigned to the car when it is manufactured, hence VIN can uniquely identify a tuple in the relation.
Similarly, License Plate Number is a unique number assigned to the car by the government when it is registered and hence it can be uniquely identify a tuple in the relation.
The candidate keys for the above relation are Vehicle Identification Number(VIN) and License Plate Number
Any of the candidate keys can be selected as primary key.
For the above relation , we can select either of the candidate keys as primary key. For instance, we can select Vehicle Identification Number(VIN) as primary key and License Plate Number as alternate key for the above relation.
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