Chapter 6: Databases and Information Management
6.1- Organizing Data in a Traditional File Environment
Information systems provides users accurate (free of errors), timely (when its available to
decision makers) and relevant (when its useful) information.
File organization Terms and Concepts
1. Bit- represents smallest unit of data
2. Byte- a single character, letter, number or symbol
3. Field- grouping of characters into a word/sentences.
4. Record- a group of related fields EG. student names, course taken, grade and date
5. File- group of records of the same type.
6. Database- a group of related files
7. Entity- a person, place, thing or event
8. Attributes- characteristic describing an entity EG. Student ID , course, grade and date
Problems with the traditional file environment
Each application requires its own file and its own computer programs. Eg. HR has a personnel
master file, a payroll file, medical insurance file, a pension file….. etc….
There are resulting problems such as:
Data redundancy and Inconsistency- data redundancy is duplicate data in multiple data files
(stored in more than one place). It occurs when different groups of organization collect the
same amount of data. Data inconsistency is the same attribute, but may have a different value.
Program-Data Dependence- coupling of data stored in files and specific programs required to
update and maintain those files so that changes in programs require changes to the data.
Lack of flexibility- file system deliver routine reports after extensive programming efforts, but it
cannot deliver ad hoc reports or respond to unanticipated information requirements.
Poor Security- Management cannot track who is accessing and making changes to
organization’s data because there is little control or management of data. Lack of Data Sharing and Availability- it is impossible for information to be shared or accessed
in a timely manner. Information cannot flow freely to different parts of the organization.
6.2 The Database Approach to Data Management
Data is stored so it appears to users being stored only in one location
Database Management Systems:
Database Management Systems (DBMS) is software that permits an organization to centralize
data, manage them efficiently, and provide access to the stored data. It acts as an interface
between applications and data files. DBMS relieves programmer from the task of understanding
where/how the data is stored.
Logical view presents data as it would be perceived by business specialists
Physical views show how data are actually stored, structured and organized.
How a DBMS solves the problems of the traditional file environment: reduces data redundancy
and inconsistency by minimizing isolated files. It may not enable the organization to eliminate
data redundancy. DBMS uncouples programs and data, enabling data to stand on its own.
Access and availability of information is increased. It enables the organization to centrally
manage data, their use, and security through use if a data dictionary.
Relational DBMS: most popular type of DBMS today for PC’s as well as for larger computers
and mainframes is the relational DBMS. It represents databases as 2-D tables. They are also
referred to as files. For example: Microsoft Access is an example of relationa