Data Modeling (UML) Answers Part 2

43. Identify the classes and associations in the following narrative and draw a class diagram with multiplicities: To put himself through school, Zach operates an ice cream truck that travels through neighborhoods, ringing a bell to attract kids that want a cold ice cream treat. Zach's inventory includes many ice cream products and he tracks which items are sold in each sale. He occasionally adds new items to his list of ice cream products for sale. Zach only accepts cash for each sale. To identify the routes that generate the most sales, Zach summarizes sales by neighborhood but he only tracks neighborhoods with at least one sale. Zach deposits the cash received in his bank account at the end of each day. 44. Identify the classes and associations in the following narrative and draw a class diagram with multiplicities: Barb maintains a real estate tracking system for Orange County. There are currently 34 incorporated cities and 15 unincorporated communities in the county. Barb tracks all of these as cities. Within each city, there is at least one and could be many neighborhoods. Within each neighborhood, there is at least one and likely many houses. For each house, Barb tracks information for all the sales in the last 20 years, although some houses have not been sold in the last 20 years. 45. List the tables with primary keys, attributes, and foreign keys that implement the following UML Class diagram given the accompanying list of attributes. Data Modeling Answer Key True / False Questions 1. The Object Management Group maintains the standard for Unified Modeling Language (UML) Class diagrams. TRUE 2. Unified Modeling Language (UML) Class diagrams describe the logical structure of a database system. TRUE 3. A Class is a separately identifiable collection of business relationships. FALSE 4. In Unified Modeling Language (UML) Class diagrams, a Class is represented by a rectangle. TRUE 5. In Unified Modeling Language (UML) Class diagrams, Associations are represented by dashed lines. FALSE 6. In Unified Modeling Language (UML) the options for minimum multiplicity values are 0, 1, and 2. FALSE 7. In Unified Modeling Language (UML) the options for maximum multiplicity values are 1 and *. TRUE 8. In Unified Modeling Language (UML) the options for maximum multiplicity values are 0 and *. FALSE 9. In Unified Modeling Language (UML) the options for minimum multiplicity values are 1 and *. FALSE 10. In Unified Modeling Language (UML) attributes are characteristics of individual instances of a Class. TRUE 11. In Unified Modeling Language (UML) primary keys cannot by NULL. TRUE 12. In Unified Modeling Language (UML) primary keys may be blank. FALSE 13. In Unified Modeling Language (UML) foreign keys allow tables to be linked together in a database. TRUE 14. A generalization relationship models a grouping of things that share common characteristics. TRUE 15. An aggregation relationship is a form of generalization relationships. FALSE 16. Associations can indicate the roles that one Class takes in its business relationship with another Class. TRUE 17. A database should have exactly the same number of tables as there are Classes in the Unified Modeling Language (UML) Class diagram from which the database is developed. FALSE 18. When building a database from Unified Modeling Language (UML) Class diagrams, each instance of each Class becomes a row in the corresponding table. TRUE 19. Obligatory business rules state what should not occur. FALSE 20. Business rules set criteria for branching in activity models. TRUE Multiple Choice Questions 21. Which of the following is not something a model of database structures must be able to describe? A. The entities or things in the domain of interest B. The sequence that entities are accessed C. The cardinalities that describe how many instances of one entity can be related to another D. The attributes or characteristics of the entities and relationships 22. Which of the following would be least likely to be represented with a Unified Modeling Language (UML) Class? A. Truck s B. The number of trucks used in the delivery C. The employee driving the truck D. The customer receiving the delivery 23. Which of the following is the best description of an association? A. A group of classes B. The lines in a UML Class diagram C. The relationship between two classes D. The number of times one class is related to another 24. Which of following are possible options for minimum multiplicities? A. 0 and 1 B. 0 and * C. * and 1 D. 0, 1, and * 25. Which of the following best describes the purpose of a primary key? A. Allows linking two or more tables B. Indicates the minimum multiplicities for an association C. Matches values of foreign keys in other classes D. Uniquely identifies each instance of the class 26. Which of the following statements about foreign keys is not true? A. A foreign key can be a combination of attributes. B. A foreign key cannot be NULL. C. Foreign key must match values of the linked primary key. D. Foreign keys support a defined association. 27. Which of the following is not a criterion for selection of a primary key? A. The primary key cannot be NULL (blank). B. The primary key should be controlled by the organization assigning it. C. Primary keys with sequential values make it easier to spot gaps in the data. D. Longer key values are better than shorter key values. 28. Which of the following is not a best practice in preparing Unified Modeling Language (UML) Class diagrams? A. Opt for simplicity. B. Model each process separately. C. Avoid crossing lines whenever possible. D. Avoid confusing abbreviations. 29. Which of the following is not a step in using a Unified Modeling Language (UML) Class model to prepare a database? A. Map Classes to Tables. B. Map Attributes to Table Fields. C. Map Associations to Primary Keys. D. Map Associations to Foreign Keys.