Transcript Chapter 1 Information Systems Overview

Database Management
An Introduction
Goals For Today:
Describe why databases have become so
important to modern organizations
 Describe what database and database
management systems are and how they work.
 Explain four emerging database trends:
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(1) client / server computing,
(2) object-oriented databases,
(3) data mining, and
(4) integrating Web applications
Database Defined
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Database:
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A collection of related data organized in a way
that facilitates data searches.
What are some examples of Databases?
Example of a Student Database
Types of Data Collected in a Typical Student Database
Databases
Before the Use of Computers
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Data was stored in:
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books
ledgers
card files
folders
file cabinets
or simply in people’s heads!?
Computers make the process of
storing and managing data easier
The Database Approach
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Database Management System
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software application which allows you to
create, store, organize, and retrieve data from a
single database or many databases.
Example: MS Access
Entity
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something you collect data about
Examples: people or classes
A Database Contains
the Following:
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Tables
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Fields
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how entities are represented in a database,
where each row is a record and each column a
field.
individual pieces of information
Record
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collection of related fields within one entity
Sample Data Table
(page 2-94 in your book)
Key Database Issues
and Activities
Entering and Querying Data
 Creating Database Reports
 Data Structure
 Data Type
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Entering Data
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Data Entry:
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process of getting information into a database
possible methods of data entry:
 Data
Entry Professional, Electronic Files, Historical
Records, or Web Based (Forms)
Querying Data
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Querying:
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how we get information from a database
Structured Query Language (SQL):
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most common language used to interface with
databases
Example:
SELECT DISTINCTROW STUDENT_ID, GRADE
FROM GRADES
WHERE GRADE = “A”
ORDER BY STUDENT_ID;
Querying Data continued
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Query By Example (QBE)
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enables you to fill out a grid, or template, in
order to construct a description of the data you
would like to retrieve.
Creating Database Reports
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Report:
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A compilation of data from the database that is
organized and produced in a printed format.
Typically produced on paper, but also can be
displayed on-screen.
Example: Quarterly Sales Report
Data Structure
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Database has two parts:
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Data Model:
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Data
Data Structure: how the data is organized.
representation of entities and their relationships
to the real world
Primary Key:
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a unique identifier in the database
one or more fields
Data Structure continued
Primary Key is Student ID
Data Type
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Data Type:
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each field in the database needs to be of a
certain type
Examples: text, number, dates
Data Dictionary:
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a document (often published online) prepared
by the database designers to aid users in data
entry.
Data Dictionary Example:
Students Table
Primary Key
yes
no
no
Field Name
Student ID
Last Name
First Name
Field Type Field Length
Number
9
Text
20
Text
15
Database Management
Systems Approaches
The Hierarchical Model
 The Network Model
 Relational Model
 Normalization
 Associations
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The Hierarchical Model
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Records in parent entities can have many
child records, but each child can have only
one parent.
Parent
Child
The Network Model
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In this case you can have multiple children
and parents
Parents
Children
The Relational Model
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A good relational database design eliminates
unnecessary data duplications and is, therefore,
easier to maintain
Relationship: joining two tables on a common
field
Relationship
Normalization
A technique used to make complex databases
more efficient and easier to handle
 Eliminates Redundant Data
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Normalization continued
Database w/redundant data
Database after
Normalization
Three Types of
Associations or Relationships
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One-to-One
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One-to-Many
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Each team has only one home stadium, and each home stadium
has only one team
– Team ID Team Name Location Stadium ID
Each Player is on only one team, but each team has many
players
– Player ID Player Name Position
Team ID
Many-to-Many
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Each player participates in many games, and each game has
many players
Team 1 Team 2 Date Player ID Points Minutes Fouls
Recent Developments Affecting
Database Design and Use
Databases and Client / Server Computing
 Object-Oriented Databases
 Data Mining
 Linking Web Site Applications to
Organizational Databases
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Databases and Client / Server
Computing
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Database application is divided into two parts:
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Database Server
 where
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all data is stored on a powerful machine
PC Client
 the
program used to manipulate the data resides on an
individual user’s computer
Object-Oriented Databases
treat tables, queries, and other components
as generic reusable OBJECTS (rather than
data) that can be mixed and matched and
used in many applications (e.g. MS Excel
and MS Access).
 Most of today’s database applications have
some of these Object characteristics.
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Data Mining
Allows companies to sort and analyze
information to better understand customers,
products, markets, or any other phase of
their business for which data has been
captured.
 Example: Grocery Store Club Cards
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Data Mining continued
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Data Warehouses
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An integration of multiple, large databases and
other information sources into a single
repository or access point that is suitable for
direct querying, analysis, or processing
Data Warehouse Examples
TELECOMMUNICATIONS
Analysis of the following:
Call volumes
Equipment sales
Customer profitability
Costs
Inventory
Purchasing leverage with suppliers
Frequent buyer program management
REPRESENTATIVE COMPANIES
AT&T
Ameritech
Belgacom
British Telecom
Telestra AustraliaTelecom Ireland
Telecom Italia
Data Mining continued
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Data Marts
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A small-scale data warehouse that contains a
subset of the data for a single aspect of a
company’s business
Examples: finance, inventory, or personnel
Linking Web Site Applications to
Organizational Databases
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Example:
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many comapies are enabling users of their Web
Site to:
view product catalogs,
 check inventory, and
 place orders
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these are all actions that read and write to the
organizations’ databases.
Goals For Today:
Described why databases have become so
important to modern organizations
 Described what database and database
management systems are and how they work.
 Explained four emerging database trends:

–
–
–
–
(1) client / server computing,
(2) object-oriented databases,
(3) data mining, and
(4) integrating Web applications