Chapter 1 - Introduction to Databases

1. CS3270
DATABASE – I
Mr. Dilawar
Lecturer,
Computer Science Faculty,
Bakhtar University
Kabul, Afghanistan.

2. Course Objectives
After successfully completing this course, you will be able to:
• Understand the underlying concepts of database, and database management
system (DBMS).
• Learn the concept of relational data model.
• Analysis and design of database application or information system.
• Experience with SQL.
• Implement the database using SQL.
• Learn to work with Microsoft SQL Server environment.

3. Course Outline
• Introduction to Databases
• Database Environment
• Database Architecture and the Web
• The Relational Model
• Relational Algebra and Relational Calculus
• SQL: Data Manipulation
• SQL: Data Definition

4. Course Outline
• Database Planning, Design, and Administration
• Fact-Finding Techniques
• Entity-Relationship Modeling
• Enhanced Entity-Relationship Modeling
• Normalization
• Advanced Normalization
• Design Methodologies

5. Text Books to Follow
• Database Systems: A Practical Approach to Design, Implementation, and
Management, Connolly, T. M., and Begg, C. E. 6th Edition, Addison Wesley, 2015.
• Modern Database Management, Hoffer, Jeffrey A., and Prescott, Mary B., and
McFadden, Fred R. 10th Edition, Prentice Hall, 2011.
• Database Processing Fundamentals, Design and Implementation, Kroenke, David
M. 12th Edition, Prentice Hall.
• An Introduction to Database Systems, Date, C. J. 8th Edition, Addison Wesley,
2003.

6. Introduction to Databases
Chapter – 1

7. Lecture Outline
• Introduction
• Traditional File-Based Systems
• Database Approach
• Roles in the Database Environment
• History of DBMS
• Advantages and Disadvantages of DBMSs

8. Introduction
• Collection of logically related data is called database.
• A database may be of any size and complexity.
• Salesperson may contain a small database of customer contacts.
• A large corporation may build a large database.

9. Introduction
• Other examples of database applications can be:
• Purchases from the supermarket.
• Purchasing using your credit card.
• Booking a holiday at the travel agent.
• Using the local library.
• Using the internet.
• Studying at university.

10. Introduction
• A software or tool that is used to manage and control the access to
the database is called database management systems.
• A database application is simply a program that interacts with the
database at some point in its execution.
• A database system is a collection of application programs that interact
with the database along with the DBMS and database itself.

11. Traditional File Processing System
• File-based system is a collection of application programs that perform
services for the end-users such as the production of reports.
• Each program defines and manages its own data.
• Early attempt to computerize the manual filing system.
• Files in cabinet and locks for security.
• For searching we may have indexing system that helps locate what we want quickly.
• Works well
• While number of items to be stored is small.
• For only storage or retrieval functionality of large number of items.

12. Traditional File Processing System
• The manual system becomes more inefficient while processing the
information in the files.
• Typical real estate agent’s office holds two separate files:
• File for each property for sale or rent.
• File for each buyer and renter, and each member of staff.

13. Traditional File Processing System
Sales Department
Contract Department

14. Traditional File Processing System
• Consider the efforts that would be required to answer the following
questions:

15. File-Based Approach
• The file-based system was developed in response to the needs of
industry for more efficient data access.
• Based on decentralized approach, where each department, with the
assistance of Data Processing (DP) staff, stored and controlled its own data.
• Consider the DreamHome example.

16. File-Based Approach

17. File-Based Approach
• Significant amount of duplication of data.
• Before to discuss the limitations, it is useful to understand the
terminology used in file-based systems.
• A file is simply a collection of records, which contains logically related data.
• For example, the PropertyForRent file contains six records, one for each property.
• Each record contains a logically connected set of one or more fields.
• Each field represents some characteristics of the real-world object that is being modeled.

18. Limitations of File-Based Approach
• Separation and isolation of data
• Each program maintains its own set of data.
• Users of one program may be unaware of potentially useful data held by
other programs.
• Duplication of data
• Decentralized approach taken by each department.
• Same data is held by different programs.
• Wasted space, money and time and perhaps more importantly data integrity;
in other words data consistency.

19. Limitations of File-Based Approach
• Data Dependence
• File structure is defined in the program code.
• Also known as a Program-Data dependence.
• Incompatible file formats
• Programs are written in different languages, and so cannot easily access each
other’s files.
• Fixed Queries/Proliferation of application programs
• Programs are written to satisfy particular functions.
• Any new requirement needs a new program.

20. Database Approach
• All the above limitations of file-based approach can be listed as:
• The definition of the data is embedded in the application programs, rather
than being stored separately and independently.
• There is no control over the access and manipulation of data outside that
forced by the application programs.
• The above limitations were overcome with the new approach called
database approach (database and DBMS).

21. The Database
• A shared collection of logically related data, and a description of this
data, designed to meet the information needs of an organization –
Database.
• Integrated with a minimum amount of duplication.
• Shared corporate resource.
• Also holds the description of the data.
• Description of data is known as the system catalog (or data dictionary
or metadata – the ‘data about data’).
• Data abstraction.

22. Database Management System
• A software system that enables users to define, create, maintain, and
control access to the database.
• The DBMS is the software that interacts with the users’ application
programs and the database.

23. Database Management System
• Typically, a DBMS provides the following facilities:
• It allows users to define the database, usually through a Data Definition
Language.
• The DDL allows users to specify the data types and structures and the constraints on the
data to be stored in the database.
• It allows users to insert, update, delete, and retrieve data from the database,
usually through Data Manipulation Language (DML).
• It provides controlled access to the database.
• Data security, data integrity, concurrency control system, recovery control system, and a
user-accessible catalog.

24. (Database) Application Programs
• A computer program that interacts with the database by issuing an
appropriate request (typically an SQL statement) to the DBMS.
• The programs might be a desktop application or an online application.
• The application program may be written in some programming
languages or in some 4GL.

25. (Database) Application Programs

26. (Database) Application Programs
• Allows each user to have his or her own view of the database – View.
• A view is essentially some subset of the database.
• The benefits of views are:
• Reduce complexity.
• Provide a level of security.
• Provide a mechanism to customize the appearance of the database.
• Present a consistent, unchanging picture of the structure of the database,
even if the underlying database is changed.

27. Components of the DBMS Environment

28. Roles in the Database Environment
• Data Administrator (DA)
• The DA is responsible for the management of the data resource including
database planning, development and maintenance of standards, policies and
procedures.
• Database Administrator (DBA)
• Physical realization of the database.
• Physical database design and implementation.
• Security and integrity control.
• Maintenance of the operational system.
• Ensuring satisfactory performance of the applications for users.

29. Roles in the Database Environment
• Database Designers (Logical and Physical)
• The logical database designer must have a thorough and complete
understanding of the organization’s data and any constraints on this data.
• Identifying the data (entities, attributes, relationships, and constraints).
• Constraints are some called business rules.

30. Roles in the Database Environment
• Database Designers (Logical and Physical)
• The physical database designer decides how the logical database design is to
be physically realized.
• Mapping the logical database design into a set of tables and integrity constraints.
• Selecting specific storage structures and access methods for the data to achieve good
performance.
• Designing any security measures required on the data.

31. Roles in the Database Environment
• Application Programmers
• Once the database is implemented, the application programs that provide the
required functionality for the end-users must be implemented.
• End Users (naive and sophisticated)

32. History of Database Management Systems
• Roots of the DBMS
• Apollo moon-landing project, 1960s.
• NAA (North American Aviation), prime contractor for the project.
• Developed a software GUAM (Generalized Update Access Method),
hierarchical.
• In mid – 1960s IBM joined NAA, result was IMS (Information Management
System).

33. History of Database Management Systems
• IDS ( Integrated Data Store)
• By General Electric, network, mid-1960.
• CODASYL (Conference on Data Systems Languages)
• DBTG (Data Base Task Group)
• Proposal in 1971.
• Network schema, subschema, and data management language.
• DDL, subschema DDL, and DML.

34. History of Database Management Systems
• E. F. Codd, 1970
• IBM Research Laboratory
• Relational model
• Result of this project
• Development of SQL
• Commercial relational DBMS products e.g. DB2, SQL/DS from IBM, Oracle from Oracle
Corp.

35. Advantages of DBMSs
• Control of data redundancy
• Data consistency
• More information from the same amount of data
• Sharing of data
• Improved data integrity (constraints)
• Improved security (authentication, rights)
• Enforcement of standards (data formats, naming conventions,
documentation etc.)

36. Advantages of DBMSs
• Economy of scale (economical cost)
• Balance conflicting requirements
• Improved data accessibility and responsiveness (ad hoc queries)
• Increased productivity (developer)
• Improved maintenance through data independence
• Increased concurrency
• Improved backup and recovery services

37. Disadvantages of DBMSs
• Complexity
• Size (disk space for DBMS)
• Cost of DBMS
• Additional hardware costs
• Cost of conversion
• Performance
• Higher impact of a failure

38. Summery
• Introduction
• Traditional File-Based Systems
• Database Approach
• Roles in the Database Environment
• History of DBMS
• Advantages and Disadvantages of DBMSs

39. Thank You
For your Patience