Database Reference
In-Depth Information
D
APPENDIX
ANSWERS TO ODD-NUMBERED
REVIEW QUESTIONS
CHAPTER 1
INTRODUCTION TO DATABASE MANAGEMENT
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1. Redundancy is the duplication of data or the storing of the same data in more than one place.
Redundancy wastes space, makes the updating of data more cumbersome and time-consuming,
and can lead to inconsistencies.
3. An entity is a person, place, object, event, or idea for which you want to store and process data.
An attribute, which is also called a field or column in many database systems, is a characteristic
or property of an entity.
5. A database is a structure that can store information about multiple types of entities, the attributes
of those entities, and the relationships among the entities.
7. An E-R diagram represents a database in a visual way by using a rectangle for each entity, using a
line to connect two entities that have a relationship, and placing a dot at the end of a line to indi-
cate the
part of a one-to-many relationship.
9. Database design is the process of determining the table structure of the desired database.
11. It is possible to get more information from the same amount of data by using a database approach
as opposed to a nondatabase approach because all data is stored in a single database, instead of
being stored in dozens of separate files, making the process of obtaining information quicker,
easier, and even possible in certain situations.
13. The DBA (database administrator or database administration) is the central person or group in an
organization in charge of the database and the DBMS that runs the database. The DBA attempts
to balance the needs of individuals and the overall needs of the organization.
15. An integrity constraint is a rule that the data in a database must follow. A database has integrity
when the data in it satisfies all established integrity constraints. A good DBMS should provide an
opportunity for users to incorporate these integrity constraints when they design the database.
The DBMS then should ensure that these constraints are not violated.
17. Data independence is the property that lets you change the structure of a database without
requiring you to change the programs that access the database. With data independence, you
easily can change the structure of the database when the need arises.
19. The more complex a product is in general (and a DBMS, in particular, is complex), the more
difficult it is to understand and correctly apply its features. As a result of this complexity, serious
problems may result from mistakes made by users and designers of the DBMS.
21. The great complexity of a database structure makes recovery more difficult. In addition, many
users update the data at the same time, which means that recovering the database involves not
only restoring it to the last state in which it was known to be correct, but also performing the
complex task of redoing all the updates made since that time.
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many
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