1. Web-Enabled Decision Support Systems
Introduction to Databases
Prof. Name
Position (123)
University Name

2. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

3. Introduction
The desire to collect, organize, and easily access information predates computer technology
Oral records
Written records (books)
Computers, like books, have altered the way we collect, store, and retrieve information
A database is a computer solution for fast, efficient, accurate, and secure data access
Play a crucial role in the growing dominance of internet-based technology
Used for a variety of purposes:
Online shopping
Driving directions
Class enrollment and online grades

4. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

5. Data
The term data refers to known facts that can be recorded and preserved
Include text, graphics, images, and/or video
Data in Context

6. Information
Information is the processed data presented in a form suitable for human interpretation
The same data can be processed in a variety of ways to generate different kinds of information
Information – Pie Chart

7. Metadata Metadata is data about data
Process of information building demands an additional description of data to be processed
Metadata

8. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

9. Evolution of Database Systems
Two approaches to convert data to information:
File-based
Developed in 1980’s
Stores, manipulates, retrieves data from large flat files
Database (relational systems)
Developed by E. F. Codd of IBM in the early 1980's
Widely used today
Evolution of
Database
Systems

10. File-Based Approach A file is a collection of related information
A system of files and collection of application programs manipulating them is a file-based system
The University’s
File-Based System

11. Limitations of File-Based Approach
Efforts for query answering:
What is the average grade for Dr. John Doe’s students?
List the activities for all students enrolled in EZZ 4162.
Which personnel are students as well as staff?
Other limitations:
Duplication of data
Data dependency
Slow development, high maintenance and fixed queries

12. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

13. The Database System Limitations of file-based approach tell us that:
Parameters defining data should be separately stored
There should be a way to control and manipulate data in isolation of the application program
A database management system (DBMS) is a piece of software that allows a user to define, create, and manage access to a database
Decouples application programs from data
The database stores all its data in one location, thereby limiting data duplication
A database system can be defined as the combination of a database, a DBMS, and application programs
Because of the advantages offered by a DBMS, businesses and organizations prefer the database approach to the file-based approach

14. University’s Database System

15. Components of a Database System
There are four components in any database system:
Users
Database application
DBMS
Database
Components of a
Database System

16. Components of a Database System (cont.)
A collection of logically related data
Database management system (DBMS):
Software that allows users to define, create, and manage database access
Popular database management systems:
Access, Oracle, IBM’s DB2, and SQL Server
Database applications:
Computer programs that allow users to manipulate the data in a DBMS through a user-friendly interface
Can be divided into four broad categories:
Personal: Restricted to a single user
Departmental: Referenced by hundreds of users over a shared system or network
Enterprise: Extensions of departmental applications involving thousands of users
Internet: Largest form of information sharing wherein billions of users are involved

17. Components of a Database System (cont.)
Database administrator, system developer, and end user:
A database administrator (DBA) is a person responsible for all the data resources of an organization
Uses tools that come with a DBMS to improve the productivity and performance of database planning and design
System developers are a group of people responsible for the creation of new application programs that cater to the user requirements
Use their own tools to write programs that communicate with the DBMS
End-users in an organization can add, update, and delete data in a database through application programs or directly through a DBMS
Use the application program to accomplish their day-to-day tasks

18. Functions of a DBMS
A DBMS is primarily responsible for providing a logical view of underlying data
Allows its user to store, retrieve, and update data in the database
Provides a clear and logical view of the process that manipulates the data
Other functionalities:
Data independence
Maintain segregation between the program and the data
Concurrency control
Recovery services
Utility services
Perform initialization and maintenance operations on a database

19. Advantages and Disadvantages of Database Approach
Segregation of the application program and the data
Minimal data duplication
Ability to retrieve data easily
Reduced development time and maintenance needs
Disadvantages:
Complexity
Size
Cost

20. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

21. Database Development Process
Enterprise modeling:
Describes the data needed for database system
Conceptual database modeling:
Entity-relationship (E-R) modeling
Logical database design:
Relational data modeling is used to transform the E-R diagram into a relational schema
Physical database design and creation:
Selection of software (DBMS) and hardware

22. Schema
The process of database development can also be explained using schema, an overall description of the database
Three types of schemas, defined by their levels of abstraction:
External schema:
Describes the database in terms of data viewed by different users
Conceptual schema:
Describes the database in terms of entities, attributes, and relationships, along with its integrity constraints
Internal schema:
Describes the database in terms of stored records, data fields, and indexes

23. Three-Tier Architecture

24. Database Development Process

25. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

26. Data Models
A data model is a collection of concepts for describing data, its relationships, and its constraints
Provides a clearer and more accurate description and representation of data
Standard platform that enables database designers and end-users to communicate
Come in three varieties:
Object-based models (conceptual schema)
Record-based models (external schema)
Physical data models (internal schema)

27. Object-Based Data Models
Object-based data models use entities, attributes, and relationships to present information
An entity is a living or non-living object in the real world
Examples: Person, place, event
An attribute is a property of an entity
Examples: Name, address of a person
A relationship is an association between entities
Example: Register is a relationship between student and courses
Some common types of object-based data models include:
Entity-relationship data model
Functional data model
Object-oriented data model

28. Entity-Relationship Data Model
The entity-relationship model has emerged as one of the most popular and widely used techniques in today's databases
Describes data in the form of an E-R diagram:
Entities are rectangles (“Student” and “Department”)
Relationships are diamonds (“Belongs to”)
Attributes are ovals (“SSN”, “Name”)
Cardinalities are constraints on relationships (“>” and “|”)
Entity-Relationship Diagram

29. Record-Based Data Models
Record-based data models use records to present data
A record is a structure that contains a fixed number of fields to hold a piece of information
There are three main types of record-based data models:
Relational data models
Based on mathematical concepts of relations
Use tables (or relations) to represent data and relationships
Network data models
Hierarchical data models

30. Relational Data Models
Each table consists of a fixed number of named columns (attributes) and an arbitrary number of unnamed rows (records)
University
Relational
Data Model

31. Transforming the E-R Data Model to the Relational Data Model
The E-R model and the relational model are actually closely related:
Entities in the E-R model become tables in the relational model
Attributes of in the E-R model are the table columns in the relational model
Relationships in the E-R model are represented by a common attribute

32. Overview 2.1 Introduction 2.2 Data, Information, and Metadata
2.3 File-Based Approach
2.4 Database Approach
2.5 Database Development Process
2.6 Data Models
2.7 Summary

33. Summary Data are known facts that can be recorded and preserved
Information is the processed data presented in a form suitable for human interpretation
Metadata is data about data
There are two approaches to convert data to information:
Traditional file-based approach
A system of files and the collection of computer programs manipulating them
Modern database approach
A database system consists of a combination of a database, a DBMS, and application programs

34. Summary (cont.)
A database is an organized collection of logically related data.
A database management system is software that allows users to define, create, and manage database access.
Database applications are computer programs that allow users to manipulate data in a DBMS through a user-friendly interface.
A database administrator (DBA) is a person or group of people responsible for all the data resources of an organization.

35. Summary (cont.)
The database development process consists of four steps:
Enterprise modeling
Conceptual database modeling
Logical database design
Physical database design and creation
The process of database development can also be explained through the schema, an overall description of the database
External schema:
Describes the database in terms of data viewed by different users
Conceptual schema:
Describes the database in terms of entities, attributes, and relationships along with integrity constraints
Internal schema:
Describes the database in terms of stored records, data fields, and indexes

36. Summary (cont.)
A data model is a collection of concepts for describing data, its relationships, and its constraints
Object-based data models use entities, attributes, and relationships to present information
The entity-relationship data model is an example of object-based model and describes data in the form of an E-R diagram
Record-based data models use records to present data
Relational data model is based on mathematical concepts of relations and is an example of record-based model

37. Additional Links
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