DBMS Database Management System - Technical Questions and Answers

11.	Discuss the alternative terminology that is used in the relational model.
	Answer: Relations are also called tables, and sometimes by the older data processing term files. A row is known as a tuple in the relational model, but may also be referred to as a record. Finally, relational model attributes are known as table columns and sometimes as fields. Workspace Report errors ... Name : Email: View Answer

12.

Why are functional dependencies not equations?

13.

What is a foreign key, and what is it used for?

14.

What are insertion and deletion anomalies?

15.

What does it mean when we say that a relation is in Boyce-Codd Normal Form (BCNF)?

16.	You have been given a set of tables with data and asked to create a new database to store them. When you examine the data values in the tables, what are you looking for?
	Answer: (1) Multivalued dependencies, (2) Functional dependencies, (3) Candidate keys, (4) Primary keys and (5) Foreign keys. Workspace Report errors ... Name : Email: View Answer

17.	Why do normalized tables require more complex SQL when SQL statements are used in application programs?
	Answer: Tables that are normalized contain data that has been distributed among the tables, but which may need to be recombined to answer queries from an application. To recombine the data, the programmer will have to use subqueries and/or joins. These SQL structures are more complex to write than a simple SELECT statement. Workspace Report errors ... Name : Email: View Answer

18.	What is the multivalue, multicolumn problem? Include an example not used in the text.
	Answer: The multivalue, multicolumn problem occurs when a table is designed to include multiple columns that hold variations of one type of attribute data. One example is where boat owners have the names of their boats stored as BOAT_01, BOAT_02 and BOAT_03. Workspace Report errors ... Name : Email: View Answer

19.

Why is the multivalue, multicolumn problem another form of the multivalued dependency problem?

20.	What is the inconsistent values problem? Include an example not used in the text.
	Answer: The inconsistent values problem occurs when different users or data sources use slightly different forms of the same data value. One example is where automobiles are specified as "Ford, 2-door, Red" in one cell and "Red Ford 2-door" in another. Workspace Report errors ... Name : Email: View Answer