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Unformatted text preview: Chapter 6, Relational Database Design: Converting Conceptual REA Models to Relational Databases True/False Questions 1. The REA conceptual model can be implemented only with relational database software. Ans: False Response: You could also use object-oriented software or other implementation tools. 2. A conceptual database model is independent of any particular database software package. Ans: True 3. A physical database model is independent of any particular database software. Ans: False Response: Such a model is created based on the software package in which the database is implemented and is therefore dependent on the software choice. 4. In the relational database model each table represents either an entity or a relationship between entities. Ans: True 5. The order in which columns are placed in a relational database table is crucial to maintain referential integrity. Ans: False Response: The order of columns is immaterial. 6. Entity integrity refers to a primary key that will allow null values. Ans: False Response: Entity integrity prohibits a primary key from having null values. 7. The following pet table PetName Shots Received Date Sydney PV, RV,AB,CD Aug-09 Sam AC,DC,BC Sept- 01 is a good example of a relational table. Ans: False Response: The table contains multiple facts in one place (a repeating group) Dunn/Cherrington/Hollander, Enterprise Information Systems: A Pattern Based Approach, 3e 79 Chapter 6, Relational Database Design: Converting Conceptual REA Models to Relational Databases 8. In the following pet table PetName Shots Received Date Sydney PV, RV,AB,CD Aug-09 Sam AC,DC,BC Sept- 01 the shots received column is a repeating group because the column contains multiple values. Ans: True 9. When converting a REA model into relational tables, each entity object becomes a relation. Ans: True 10. The rule for converting relationships for which the maximum participation cardinalities are many for both entities is to post the primary key of either entity into the table of the other entity. Ans: False Response: You must create a separate table with the key attributes from both entity tables as a concatenated primary key. 11. A concatenated relationship key contains fields from one relational database table. Ans: False Response: A primary key of a relationship is made up of primary keys from the two or more related entities. 12. Efficient database design avoids null values as much as possible and uses the least amount of tables. Ans: True 13. Relationships may have attributes; these attributes should be attached to the relationship on an entity-relationship diagram or listed in the relationship section of an entity- relationship grammar....
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This note was uploaded on 01/17/2011 for the course INFO SYSTE ACC 115 taught by Professor Baker during the Spring '10 term at Strayer.
- Spring '10