# Questions on Entity Relation Diagrams -- ERDs

1. What is an ERD? Define the term and what it looks like and what it means. Give a simple example.

2. Redraw a UML diagram (TBA) as a diagram using the Chen notation.
3. Redraw a Chen ERD (TBA) as a UML diagram.

4. Visit the Internet Movie Data Base (IMDB). List the entities and typical facts displayed. Then draw a rough and hypothetical ERD of the data base that underlies the web site.

5. Find one example of each of the ERD patterns in a domain/system that you know about.
6. Given a tally-roll or receipt parse it. Then list the identifiers on it. If each identifier in your tally-roll or receipt is the key to an Entity type derive a rough ERD for the system that produced the receipt.

7. Draw a rough (no boxes) ERD of part of CSUSB with at least 6 entities.
8. What fragment of an ERD is suggested by
` CSCI372 section 01 is taught in JBH372 at 4-6pm TuTh by RBOTTING`
Note: several solutions are possible.
9. We have 10,000 students and each student is on average enrolled in 5 sections. Each faculty, on average teaches 2.5 sections. How many faculty must we have?

10. What are the two properties of a entity type that are used to determine the total volume of data needed? What is the formula connecting these tagged values to the volume.

11. Draw a rough ERD of a Dungeon-type game: Rooms have walls. Most walls have two rooms: one on each side. Walls have doors. Doors can be open or closed. Rooms have artifacts. Characters are always in a room and a room can have any number of characters in it. Characters can carry artifacts. There are several types of artifact such as weapon, clothes, jewel, wand, .... Rooms have monsters. (Multiple answers are possible).

12. Draw an ERD describing use cases in a project: A project has many use cases. Each communicates with many actors and many actors communicate with a given use case. A Use case has a name. An actor has a name. Each user has a prime actor that achieves some goal by using that use case.

13. Draw a rough ERD of a DFD. Use these entity names: Process, Store, External Entity, Data Flow. List any constraints that can not be expressed in an ERD.

14. Draw an ERD of: A formula is the sum of many terms. A term is a product of factors. A factor can be a constant, a variable, or another formula.

## Exam Question on ERDs

Draw a simple UML class diagram (conceptual model) for a student registration data base that expresses the following facts: A student can be enrolled in many classes and a class has any number students enrolled in it. A class takes place in a unique room and in a unique time-slot. Each class is taught by a teacher. Each class is scheduled by a department, and each teacher works for a unique department. Use as many names as possible for the above description, You may have to invent some names. No flowcharts! Hide attributes and operations.

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# Abbreviations

1. TBA::="To Be Announced".
2. TBD::="To Be Done".