Access over 20 million homework & study documents

DATABASE NOTES

Content type
User Generated
Subject
Other
Type
Study Guide
Rating
Showing Page:
1/18
Database Solutions
by mohamedomara |
DATABASE SOLUTIONS (2nd Edition)
THOMAS M CONNOLLY & CAROLYN E BEGG
SOLUTIONS TO REVIEW QUESTIONS
Chapter 1 Introduction- Review questions
1.1List four examples of database systems other than those listed in Section 1.1. Some examples could
be:
•A system that maintains component part details for a car manufacturer; •An advertising company
keeping details of all clients and adverts placed with them; •A training company keeping course
information and participants’ details; •An organization maintaining all sales order information. 1.2Discuss
the meaning of each of the following terms:
(a)data
For end users, this constitutes all the different values connected with the various objects/entities that are
of concern to them. (b)database
A shared collection of logically related data (and a description of this data), designed to meet the
information needs of an organization. (c)database management system
A software system that: enables users to define, create, and maintain the database and provides
controlled access to this database. (d)application program
A computer program that interacts with the database by issuing an appropriate request (typically an SQL
statement) to the DBMS. (e)data independence
This is essentially the separation of underlying file structures from the programs that operate on them,
also called program-data independence. (f)views.
A virtual table that does not necessarily exist in the database but is generated by the DBMS from the
underlying base tables whenever it’s accessed. These present only a subset of the database that is of
particular interest to a user. Views can be customized, for example, field names may change, and they
also provide a level of security preventing users from seeing certain data. 1.3Describe the main
characteristics of the database approach. Focus is now on the data first, and then the applications. The
structure of the data is now kept separate from the programs that operate on the data. This is held in the
system catalog or data dictionary. Programs can now share data, which is no longer fragmented. There
is also a reduction in redundancy, and achievement of program-data independence. 1.4Describe the five
components of the DBMS environment and discuss how they relate to each other. (1)Hardware:The
computer system(s) that the DBMS and the application programs run on. This can range from a single
PC, to a single mainframe, to a network of computers. (2)Software:The DBMS software and the

Sign up to view the full document!

lock_open Sign Up
Showing Page:
2/18
application programs, together with the operating system, including network software if the DBMS is
being used over a network. (3)Data:The data acts as a bridge between the hardware and software
components and the human components. As we’ve already said, the database contains both the
operational data and the meta-data (the ‘data about data’). (4)Procedures:The instructions and rules that
govern the design and use of the database. This may include instructions on how to log on to the DBMS,
make backup copies of the database, and how to handle hardware or software failures. (5)People:This
includes the database designers, database administrators (DBAs), application programmers, and the
end-users. 1.5Describe the problems with the traditional two-tier client-server architecture and discuss
how these problems were overcome with the three-tier client-server architecture. In the mid-1990s, as
applications became more complex and potentially could be deployed to hundreds or thousands of end-
users, the client side of this architecture gave rise to two problems: •A ‘fat’ client, requiring considerable
resources on the client’s computer to run effectively (resources include disk space, RAM, and CPU
power). •A significant client side administration overhead.
By 1995, a new variation of the traditional two-tier client-server model appeared to solve these problems
called the three-tier client-server architecture. This new architecture proposed three layers, each
potentially running on a different platform: (1)The user interface layer, which runs on the end-user’s
computer (the client). (2)The business logic and data processing layer. This middle tier runs on a server
and is often called the application server. One application server is designed to serve multiple clients.
(3)A DBMS, which stores the data required by the middle tier. This tier may run on a separate server
called the database server. The three-tier design has many advantages over the traditional two-tier
design, such as: •A ‘thin’ client, which requires less expensive hardware. •Simplified application
maintenance, as a result of centralizing the business logic for many end-users into a single application
server. This eliminates the concerns of software distribution that are problematic in the traditional two-tier
client-server architecture. •Added modularity, which makes it easier to modify or replace one tier without
affecting the other tiers. •Easier load balancing, again as a result of separating the core business logic
from the database functions. For example, a Transaction Processing Monitor (TPM) can be used to
reduce the number of connections to the database server. (A TPM is a program that controls data
transfer between clients and servers in order to provide a consistent environment for Online Transaction
Processing (OLTP).) An additional advantage is that the three-tier architecture maps quite naturally to
the Web environment, with a Web browser acting as the ‘thin’ client, and a Web server acting as the
application server. The three-tier client server architecture is illustrated in Figure 1.4.
1.6Describe the functions that should be provided by a modern full-scale multi-user DBMS. Data
Storage, Retrieval and UpdateAuthorization Services
A User-Accessible CatalogSupport for Data Communication
Transaction SupportIntegrity Services
Concurrency Control ServicesServices to Promote Data Independence Recovery ServicesUtility
Services
1.7Of the functions described in your answer to Question 1.6, which ones do you think would not be
needed in a standalone PC DBMS? Provide justification for your answer. Concurrency Control Services -
only single user.
Authorization Services - only single user, but may be needed if different individuals are to use the DBMS
at different times. Utility Services - limited in scope.
Support for Data Communication - only standalone system.
1.8Discuss the advantages and disadvantages of DBMSs.
Some advantages of the database approach include control of data redundancy, data consistency,
sharing of data, and improved security and integrity. Some disadvantages include complexity, cost,

Sign up to view the full document!

lock_open Sign Up
Showing Page:
3/18

Sign up to view the full document!

lock_open Sign Up
End of Preview - Want to read all 18 pages?
Access Now
Unformatted Attachment Preview
Database Solutions by mohamedomara | DATABASE SOLUTIONS (2nd Edition) THOMAS M CONNOLLY & CAROLYN E BEGG SOLUTIONS TO REVIEW QUESTIONS Chapter 1 Introduction- Review questions 1.1List four examples of database systems other than those listed in Section 1.1. Some examples could be: -A system that maintains component part details for a car manufacturer; -An advertising company keeping details of all clients and adverts placed with them; -A training company keeping course information and participants' details; -An organization maintaining all sales order information. 1.2Discuss the meaning of each of the following terms: (a)data For end users, this constitutes all the different values connected with the various objects/entities that are of concern to them. (b)database A shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization. (c)database management system A software system that: enables users to define, create, and maintain the database and provides controlled access to this database. (d)application program A computer program that interacts with the database by issuing an appropriate request (typically an SQL statement) to the DBMS. (e)data independence This is essentially the separation of underlying file structures from the programs that operate on them, also called program-data independence. (f)views. A virtual table that does not necessarily exist in the database but is generated by the DBM ...
Purchase document to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Anonymous
Just what I was looking for! Super helpful.

Studypool
4.7
Trustpilot
4.5
Sitejabber
4.4

Similar Documents