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7/30/2019 Goood Databases3147

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Introduction

Database: an organized collection of dataDatabase management system (DBMS):

group of programs to manage databaseManipulates databaseProvides an interface between database and the

user of the database and other applicationprograms

Database administrator (DBA): skilled ISprofessional who directs all activities relatedto an organizations database


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The Hierarchy of Data

Bit (a binary digit): a circuit thatis either on or off

Byte: eight bits

Character: basic building blockof information Each byte represents a

character

Can be an uppercase letter,lowercase letter, numeric digit,

or special symbol Field: typically a name, number,

or combination of charactersthat describes an aspect of abusiness object or activity

Record: a collection ofrelated data fields

File: a collection of related

records Database: a collection of

integrated and related files

Hierarchy of data: bits,

characters, fields, records,files, and databases


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The Hierarchy of Data

Figure 3.1: The Hierarchy of Data


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Data Entities, Attributes, and Keys

Entity: a generalized class of people, places, orthings (objects) for which data is collected, stored,and maintained

Attribute: characteristic of an entity

Data item: value of an attribute

Key: field or set of fields in a record that is usedto identify the record

Primary key: field or set of fields that uniquelyidentifies the record


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Data Entities, Attributes, and Keys

Figure 3.2: Keys and Attributes


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The Database Approach

Traditional approach to database management:separate data files are created for each

application

Results in data redundancy (duplication)

Data redundancy conflicts with data integrity

Database approach to database management: pool

of related data is shared by multiple applicationsSignificant advantages over traditional approach


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Figure 3.3: The Database Approach to Data Management


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Table 3.2: Disadvantages of the Database Approach


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Data Modeling and the RelationalDatabase Model

When building a database, consider:

Content:What data should be collected, at what cost?

Access:What data should be provided to which users andwhen?

Logical structure:How should data be arranged to make

sense to a given user?

Physical organization:Where should data be physically

located?


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Data Modeling

Building a database requires two types ofdesigns

Logical designAbstract model of how data should be structured and

arranged to meet an organizations information needs

Physical design

Fine-tunes the logical database design forperformance and cost considerations


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Data Modeling

Data model: a diagramof data entities andtheir relationships

Entity-relationship(ER) diagrams: datamodels that use basic

graphical symbols toshow the organizationof and relationshipsbetween data


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The Relational Database Model Relational model: all data

elements are placed in two-

dimensional tables

(relations), which are the

logical equivalent of files

In the relational model Each row of a table

represents a data entity

Columns of the table

represent attributes Domain: the allowable values

for data attributes


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Manipulating Data

Figure 3.7: Linking Data Tables to Answer an Inquiry

D t b M t S t


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Database Management Systems(DBMS)

Interface between:Database and application programs

Database and the userCreating and implementing the right database

system ensures that the database will support bothbusiness activities and goals

DBMS: a group of programs used as an interfacebetween a database and application programs or adatabase and the user


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Overview of Database Types

Flat file

Simple database program whose records have norelationship to one another

Single user

Only one person can use the database at a timeExamples: Access, FileMaker, and InfoPath

Multiple user

Allows dozens or hundreds of people to access the samedatabase system at the same time

Examples: Oracle, Sybase, and IBM


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Creating and Modifying the Database

Data definition language (DDL)

Collection of

instructions/commands that

define and describe data and

data relationships in a database

Allows database creator to

describe the data and the data

relationships that are to be

contained in the schema Data dictionary: a detailed

description of all the data used

in the database


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Storing and Retrieving Data When an application requests

data from the DBMS, theapplication follows a logicalaccess path

When the DBMS goes to astorage device to retrieve the

requested data, it follows a pathto the physical location (physicalaccess path) where the data isstored


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Manipulating Data and GeneratingReports

Query-By-Example (QBE):a visual approach to developing

database queries or requests

Data manipulation language (DML): commands that

manipulate the data in a database

Structured Query Language (SQL): ANSI standard query

language for relational databases

Database programs can produce reports, documents, andother outputs


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Database Administration

Database administrator (DBA): directs orperforms all activities to maintain a database

environmentDesigning, implementing, and maintaining thedatabase system and the DBMS

Establishing policies and procedures

Employee training


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Popular Database ManagementSystems

Popular DBMSs for end users: Microsoft Access and

FileMaker Pro

Entire market includes databases by IBM, Oracle, and

Microsoft

Examples of open-source database systems: PostgreSQL

and MySQL

Many traditional database programs are now available onopen-source operating systems


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Selecting a DatabaseManagement System

Important characteristics of databases toconsider

Size of the databaseCost of the system

Number of concurrent users

Performance

Ability to be integrated with other systems

Vendor considerations


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Using Databases with OtherSoftware

Database management systems are oftenused with other software packages or the

InternetA database management system can act as a

front-end application or a back-endapplicationFront-end application: interacts with users

Back-end application: interacts with applications


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Linking Databases to the Internet

Linking databases to the Internet is important for many

organizations and people

Semantic Web

Developing a seamless integration of traditional databases with the

Internet

Allows people to access and manipulate a number of traditional

databases at the same time through the Internet


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Data Warehouses, Data Marts, andData Mining

Data warehouse: collects

business information from many

sources in the enterprise

Data mart: a subset of a datawarehouse

Data mining: an information-

analysis tool for discovering

patterns and relationships in adata warehouse or a data mart


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Data Warehouses, Data Marts, and DataMining

Table 3.5: Common Data-Mining Applications


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Business Intelligence

Business intelligence (BI):gathering the right informationin a timely manner and usableform and analyzing it to have apositive impact on business Turns data into useful

information that is thendistributed throughout anenterprise

Competitive intelligence: aspectof business intelligence limitedto information about competitorsand the ways that knowledgeaffects strategy, tactics, andoperations

Counterintelligence: steps anorganization takes to protectinformation sought by hostileintelligence gatherers


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Distributed Databases

Distributed databaseData may be spread across several smaller databases

connected via telecommunications devices

Corporations get more flexibility in how databases areorganized and used

Replicated databaseHolds a duplicate set of frequently used data


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Online Analytical Processing(OLAP)

Software that allows users to explore datafrom a number of different perspectives

Table 3.6: Comparison of OLAP and Data Mining


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Object-Oriented and Object-RelationalDatabase Management Systems

Object-oriented databaseStores both data and its processing instructions

Method: a procedure or action

Message: a request to execute or run a method


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Visual, Audio, and Other DatabaseSystems

Visual databases for storing images

Audio databases for storing sound

Virtual database systems: allow different databases to

work together as a unified database system

Other special-purpose database systems Spatial data technology: stores and accesses data according to the

locations it describes and permits spatial queries and analysis


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Video Clip

ChoicePoint http://www.youtube.com/watch?v=bWB3kEw08Gk
http://www.youtube.com/watch?v=bWB3kEw08Gkhttp://www.youtube.com/watch?v=bWB3kEw08Gk

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