1. What is a determinant?
An attribute, or set of attributes, that fully functionally determines another attribute is called a determinant.
2. What is multivalued dependency?
Multivalued means that a given value of attribute X determines multiple values of attribute Y. A functional dependency that is multivalued is called a multivalued dependency.
3. Explain the concept of a one-to-one attribute relationship. Give an example.
Each value of one attribute is related to exactly one value of another attribute and the other way around. For example, CH -> Switzerland and Switzerland ->CH (Country code -> name of country and vice versa).
4. Convert the following book table into a database in 3rd normal form.
| BOOK | |||||||||
| bookisbn | booktitle | FirstAuthor | Coauthors | Publisher | PubStreet | PubCity | PubContact | Pages | Price |
The table is not in 1st Normal Form: Coauthors is a multivalued field. The design does not violate 2nd Normal Form since there is no composite key. It does, however, violate 3rd normal form since publisher (a non-key field) determines PublStreet, PublCity, PublContact. The correct data model would look like this:
5. Draw an IDEF1X data models for the following scenario:
Some large cities (e.g., Cologne, Germany) have started a project called car-sharing to reduce the number of cars in the city and also reduce the cost of having a car available when needed by a person. One car is partially owned by several people. The number of owners per car may vary. Typically, not more than four people own one particular car. Also, each person can own a different percentage of the car, depending on how often she uses the car. Each person might own part of more than one car. Obviously, only one person can use the car at any particular time. Thus, a database is needed to keep track of reservations made for the car. Your data model should keep track of the owners of each car and the reservation of the car. Also keep track of any scheduled or unscheduled maintenance, tax payments, and insurance payments for each car.
6. Draw an E-R diagram for the following scenario:
A city has many streets and a street has many houses. Each house can have one or more apartment blocks. Each person can have more than one dwelling.
7. (True or False) Can the value of one attribute determine the multiple values of another attribute?
Answer: True
8. Put the following relationship into third normal form.
| studentSSN | studentname | courseid1 | grade1 | grade2 | grade3 | courseid2 | grade3 |
Answer:
| studentSSN | studentname |
| studentSSN | courseid | grade |
| courseid |
9. Put the following relationship into third normal form.
| playername | team | teamcolor | coachname | coach# | player# | playerposition | teamcaptain |
Answer:
| player#name | playername | playerposition | team |
| coach# | coachname |
| team | teamcolor | coach# | teamcaptain# |
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