Data Modeling - Quiz
The answers you selected are indicated below, along with text that explains the correct answers.
1.
Select the one statement about databases that is not correct.
Please select the best answer.
A.
A data model guides the way that the data elements are organized within the database.
B.
A hierarchical database model organizes data along tree-like, or parent-children, hierarchical chains.
C.
Web sites use databases for searching, cataloging, personalization, automatic site updates, and transaction processing.
D.
When modeling, the larger the grouping of data, the faster will be its speed.
The correct answer is D.
Answer D is the correct choice because it is not a true statement about databases: Large groups mean large file size, and large files are slower to process. Answer A is a true statement, since a data model is like a plan, or concept, for how the data will be organized in the actual database. Answer B is a true statement, since hierarchical databases do store and use data in tree-like hierarchies. Answer C is a true statement, as all the functions listed are indeed carried out by databases.
2.
Select the one statement below that does not correctly describe the type of data model listed.
Please select the best answer.
A.
Hierarchical databases are based on tree-like, parent/children relationships. They're also called flat file, because there are limits to the flexibility of storing and searching of data.
B.
Network databases are like hierarchical, but the "children" can have multiple "parents." They allow for more flexibility in identifying and searching on relationships across different sets of data.
C.
Relational databases are based on the metaphor of a two-dimensional table consisting of rows and columns. Common fields create the relationships.
D.
Object databases tend to be faster than hierarchical databases.
The correct answer is D.
Answer D is correct because the statement does not describe object databases. The hierarchical model is the most efficient model and results in the greatest speed of access. Answers A, B, and C all correctly describe the models they list.
3.
Why must data modeling occur before database development?
Please select the best answer.
A.
So that a database structure will be created that can record and report on the kinds of relationships between data that will be important to the users of the database.
B.
So the development team can design a new database model and implement it with markup language customizations.
C.
So that the technical members of the team will be able to advise on appropriate use of network technologies to transmit the data queries.
D.
So that the surrogate client will be able to check the data model with their accounting team for accuracy of middleware information architecture.
The correct answer is A.
You need to consider what will be stored in the database, who will be using it, and how they will be using it in order to structure the data in a useful way. Answer B is incorrect because markup languages are not used to create database structures. Answer C is incorrect because network technology concerns are outside the scope of this design problem. Answer D is incorrect because the accounting team would not be consulted for middleware concerns.
4.
Which model offers the greatest flexibility for the decision maker?
Please select the best answer.
A.
Relational
B.
Hierarchical
C.
Object
D.
Network
The correct answer is A.
The
relational model
is optimized for ad hoc queries most appropriate to the needs of the decision maker. Answer B is incorrect because the hierarchical model is rather rigid and is optimized for speed of access. Answer C is incorrect because the Object model is optimized for flexible development of large diverse databases, but does not offer the inherent query flexibility of the relational. Answer D is incorrect because the network model attempts to improve the flexibility of the hierarchical model by making it appear more like the relational. But, it's inherently not as flexible as the relational.
