Transcript Slide 1

Web-Enabled Decision Support Systems
Introduction to Databases
Prof. Name
Position
University Name
[email protected]
(123) 456-7890
1
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
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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
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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
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Data

The term data refers to known facts that can be recorded and preserved
– Include text, graphics, images, and/or video
ID
Name
Address
City
State
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Andrew
SW 16 Ave
Orlando
FL
2
Robert
23 Terrace
Boston
MA
3
Bob
52nd Avenue
Bronx
NY
4
Lee Hung
52nd Avenue
Albany
NY
5
Richard
999 Palm Bay
Detroit
MI
6
Tony
15th Avenue
Austin
TX
th
rd
Data in Context
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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
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Metadata

Metadata is data about data
– Process of information building demands an additional description of data to
be processed
Name
Data Type
Size
Description
ID
Number
4
Unique Student ID
Name
Text
50
Student name
Address
Text
200
Mailing Address
City
Text
50
Residential City
State
Text
2
Residential State
ZIP
Number
5
ZIP Code
Metadata
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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
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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
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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
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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
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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
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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
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University’s Database System
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Components of a Database System

There are four components in any database system:
– Users
– Database application
– DBMS
– Database
Components of a
Database System
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Components of a Database System (cont.)

Database:
– 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
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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
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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
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Advantages and Disadvantages of
Database Approach

Advantages:
–
–
–
–

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
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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
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Database Development Process
1.
Enterprise modeling:
– Describes the data needed for database system

Conceptual database modeling:
– Entity-relationship (E-R) modeling
1.
Logical database design:
– Relational data modeling is used to transform the E-R
diagram into a relational schema
2.
Physical database design and creation:
– Selection of software (DBMS) and hardware
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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
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Three-Tier Architecture
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Database Development Process
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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
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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)
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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
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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
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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
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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
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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
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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
32
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
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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.
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Summary (cont.)

The database development process consists of four steps:
1.
2.
3.
4.

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
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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
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Additional Links

Add links here.
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