Databases Reference
In-Depth Information
A
Appendix
Answers to Review Questions
Chapter 1
1.
Name the most important element of a relational database and its components.
Answer:
The table is the most important element of a relational database and it consists of rows and col-
umns. A field exists at the intersection of a row and a column.
2.
Which type of table relationship associates more than one record in a given table with more than one record
in another table?
Answer:
A many-to-many relationship associates more than one record in a table with more than one record
in another table.
3.
What type of key can be used to enforce referential integrity between two tables in a database?
Answer:
A foreign key can be used to enforce referential integrity between two tables.
4.
What are some reasons why using a spreadsheet is not a good alternative to using a large-scale database?
Answer:
Some reasons why a spreadsheet is not a good alternative to a large-scale database are that it's dif-
ficult to use for multiple users, it does not offer transaction control, the cells in a spreadsheet can contain any
type of data, and referential integrity controls between spreadsheets are difficult to implement efficiently.
5.
What are some of the benefits of abstraction in an object-relational database management system?
In an object-relational database management system, new datatypes can be created as aggregates
of existing datatypes and other new datatypes, enhancing adherence to standards and reusability.
Answer:
6.
What object-relational feature of Oracle eases the transition between relational and object-relational applications?
Answer:
Object views allow the developer to define an object-oriented structure over an existing relational
database table, thus easing the transition between relational and object-relational applications.
7.
What are the three steps in the ERA process for database design?
Answer:
The three steps in the ERA (entities, relationships, attributes) design process are to define the enti-
ties, then define the relationships between the entities, and then define the attributes of the entities. After one
pass through all three steps, one or more iterations may be necessary.
8.
Name the three Oracle-compliant ANSI SQL standards.
Answer:
Oracle9
i
is compliant with SQL:1992 and SQL:1999, whereas Oracle 10
g
is compliant with SQL:2003.
