CS312 Midterm Highlighted Handouts by VU Gateway

Contents

Module 04: Fact Finding Technique ..............................................................................................12 Module 05: Implementing Fact Finding Techniques ..................................................................... 16 Module 06: Process to Database Design ........................................................................................ 19 Module 07: Relational Database ....................................................................................................26 Module 08: Conceptual Data Modeling and Entity Relationship Diagram Overview...................32 Module 09: Entities, Attributes and Relationship ..........................................................................34 Module 10: Extended Entity Relationship Diagram ...................................................................... 43 Module 11: Example of Entity Relationship Diagram (ERD) .......................................................46

A. Definition of Data

Data can be referred to raw material from which we can draw conclusion after analysis or the facts from which we can infer new facts. Data has nothing to do with decision making but the data lays down foundation for decision making. Data is collected and further analyzed to convert it into information suitable for decision making. Data and information are two separate things and are not to be confused with each other.

B. Example of Data

The followings are the examples of data:

• Telephone Directory: it’s a huge collection of Data, with an internal structure of representation i.e. name, telephone number, city or address. Facts with structures are also termed as data.

Student Record on Computer: a file on computer containing data of ten thousand students is also a data. This data too have internal structure in the form of Student ID, Student Name, CGPA and likes.

1. Definition of Information

Information can be defined as processed or organized data presented in a given context so as to make it useful related to the problem in hand. When a specific set of data is analyzed or interpreted, it becomes information that is more suitable for decision making. Simply stating, data becomes information when it becomes relevant to the decision problem.

D. Examples of Information

The followings are the examples of information:

• Telephone Directory: as stated above, telephone directory is a huge set of data and when we process this set of data to get the telephone number of a specific dentist or a colleague, it becomes information.
• Student Record on Computer: a file on computer containing data of ten thousand students is again a huge set of data, converts in to information when processed to get list of a students with CGPA more than three.

E. Comparison of Data & Information

Data and information are often considered to be a synonym of each other but the truth is that there is nothing in common between these two. Both have different meaning and characteristics. Information is a subset of data, typically required set of data. Data leads to information so information is considered to be dependent of data.

F. Example to elaborate difference between Data and Information

Consider the following example to understand the difference between Data and Information:

H. Benefits of Using Databases

Consider a file storing flight routes from one city to another. Data is structured in the form of Flight ID, Origin, Destination, of Departure, Time of Departure etc. The file contains two thousand numbers of routes. This file qualifies to be called Data because it’s a huge set of structured data.

This huge data will turn into information when processed or filtered to get information about flight for a specific destination, let’s say from Lahore to Karachi on April 15th.

G. Life With& Without Database

Database is organized data with digital procedures, which is able to handle different set of data with a very large capacity. Database is a huge repository of data and it comes with ease to manage and therefore database has become a substitute for the manual handling of lots of file with very high chances and risk of data loss. Access to data has become easy and less timeconsuming activity due to the databases.

As mentioned above, advantages of using databases are enormous. Benefits of using databases vary from reducing redundancy in data to getting rid of unnecessary set of data. Without databases, loads of data is to be handled manually with many potential risks and difficult to access. With databases, it’s easy to access large set of data when required. Example of Driving License and Passport can serve as a good example in which the profile data is same but it’s repeated over again.

I. Why Database not Information Base

Databases deals with the storage or organization of data and the main focus of databases are to optimize data storage. On the other hand, information – as it is a subset of data - is all about the retrieval of specific data for different purposes. As information is dependent on data so databases are basic requirements for information which can then be used for multiple purposes.

J. Difference between Database and Database Management System (DBMS)

Database is all about design and structure of the data and DBMS works as a tool to manipulate or analyze the data inside the databases. DBMS is a whole system to manage a digital database, its storage, creation and retrieval (information). Differentiating between these two terms, Database is a huge set of data while DBMS is a tool to manage or control that data in a database with major function of data retrieval.