lecture on database

7/30/2019 Lecture on Database

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Your Interactive Guideto the Digital World

Discovering

Computers 2012

Chapter 10

Managing a Database


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Objectives Overview

Define the term,database, and explain

how a database

interacts with data andinformation

Define the term, dataintegrity, and describe

the qualities of valuableinformation

Discuss the termscharacter, field, record,

and file

Describe file

maintenancetechniques andvalidation techniques

Differentiate between a

file processingapproach and thedatabase approach

Discovering Computers 2012: Chapter 102See Page 513

for Detailed Objectives


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Objectives Overview

Discuss the functionscommon to most

database management

systems

Describe characteristicsof relational, object-

oriented, andmultidimensional

databases

Explain how to accessWeb databases

Identify database design

guidelines and discussthe responsibilities ofdatabase analysts and

administrators

Discovering Computers 2012: Chapter 103See Page 513

for Detailed Objectives


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Databases, Data, and Information

Database

Collection of

data organizedin a mannerthat allowsaccess,

retrieval, anduse of thatdata

Data

Collection of

unprocesseditems

Text

Numbers

Images Audio

Video

Information

Processed data

Documents Audio

Images

Video

Discovering Computers 2012: Chapter 104Page 514


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Discovering Computers 2012: Chapter 105Pages 514 515

Figure 10-1


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Database software,often called a database

management system(DBMS), allows users to:


Create a computerizeddatabase

Add, modify, anddelete data

Sort and retrieve dataCreate forms and

reports from the data


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Data integrity identifies the quality of the data

Garbage in, garbage out (GIGO) points out the

accuracy of a computers output depends on the

accuracy of the input



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Valuable information should have the following

characteristics:

Discovering Computers 2012: Chapter 108Pages 516 - 517

Accurate Verifiable Timely Organized

Accessible UsefulCost-

effective


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The Hierarchy of Data

Data is organized in layers

Files, records, fields, characters


Figure 10-2


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A character is one byte

Numbers, letters, space,

punctuation marks, or

other symbols

A field is a combination

of one or more related

characters

Field name

Field size

Data type


Figure 10-3


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Common data types include:


Text Numeric AutoNumber Currency

Date Memo Yes/No Hyperlink

Object Attachment


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Figure 10-4

A record is a group of related fields

A primary keyuniquely identifies each record

A data fileis a collection of related records


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Maintaining Data

File maintenancerefers to the procedures that

keep data current


Addingrecords

Modifyingrecords

Deletingrecords


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Maintaining Data

Users add new records to a file when they obtain

new data


Figure 10-5


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Maintaining Data

Users modify a record to correct inaccurate data

or update old data


Figure 10-6


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Maintaining Data

When a record no longer is needed, a user deletes

it from a file


Figure 10-7


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Maintaining Data

Validation compares data with a set of rules or

values to find out if the data is correct


Alphabetic/Numericcheck

Range check Consistency check

Completeness check Check digit Other checks


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File Processing Versus Databases


File processing system

Each department has its

own set of files Used for many years

Have data redundancy

Isolate data

Database approach

Programs and users share

data Reduce data redundancy

Improve data integrity

Share data

Allows easier access Reduces development time

Can be more vulnerable


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File Processing Versus Databases


Figure 10-10


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Database Management Systems


Figure 10-11


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A data dictionarycontains data about each file in

the database and each field in those files

Discovering Computers 2012: Chapter 1021Pages 527 528

Figure 10-12


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A DBMS provides several tools that allow users

and programs to retrieve and maintain data in the

database


Query language

Query by example

Form

Report generator


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A query languageconsists of simple, English-like

statements that allow users to specify the data to

display, print, or store

Query by example(QBE) provides a GUI to assist

users with retrieving data



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Figure 10-13


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A form is a window on the screen that provides

areas for entering or modifying data in a database


Figure 10-15


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A report generatorallows users to design a report

on the screen, retrieve data into the report

design, and then display or print the report


Figure 10-16


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A DBMS provides means to

ensure that only authorized usersaccess data at permitted times

Access privilegesPrinciple of least privilege



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A DMBS provides a variety of techniques to

restore the database to a usable form in case it is

damaged or destroyed


Backup Log

Recovery

utility

Continuousbackup


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Figure 10-17


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Relational, Object-Oriented, and

Multidimensional Databases


Figure 10-18

A data modelconsists of rules and standards that

define how the database organizes data


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A relational database

stores data in tables

that consist of rows and

columns Each row has a primary

key

Each column has a

unique name A relationship is a link

within the data


Figure 10-20


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Structured Query Language(SQL) is a query

language that allows users to manage, update,

and retrieve data


Figure 10-21


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An object-oriented database (OODB) stores data

in objects

Examples of applications appropriate for an

object-oriented database include:


Multimediadatabase

Groupwaredatabase

Computer-aided design

database

Hypertextdatabase


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Figure 10-22


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A multidimensional databasecan store data in more

than two dimensions of data

Sometimes known as a hypercube

Can consolidate data much faster than a relational database A data warehouse is a huge database that stores and

manages the data required to analyze historical and

current transactions



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Web Databases

Databases on the Web allow you to:


Shop for

products orservices

Buy or sell stocks Search for a job

Make airlinereservations

Register forcollege classes

Check semestergrades


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Web Databases


Figure 10-23

id h h i i


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Video: How a Photo Sharing Site

Keeps Its Data

Discovering Computers 2012: Chapter 1038

CLICK TO START
http://localhost/var/www/apps/conversion/tmp/scratch_6/10_PhotoStorageOnline.wmvhttp://localhost/var/www/apps/conversion/tmp/scratch_6/10_PhotoStorageOnline.wmvhttp://localhost/var/www/apps/conversion/tmp/scratch_6/10_PhotoStorageOnline.wmv


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Database Administration

It is important to have a carefully designed

database


Figure 10-24


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Database analysts and administrators are responsiblefor managing and coordinating all database activities

Database Analyst (DA)

Decides on proper fieldplacement, defines data

relationship, and identifiesusers access privileges

Database Administrator (DBA)

Creates and maintains the datadictionary, manages security,monitors performance, and

checks backup and recoveryprocedures



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Employees should learn

how to use the data in

the database effectively

Interact with database Identify new data for the

database

Maintain the database


Figure 10-25


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Summary

How data andinformation are

valuable assets toan organization

Methods formaintaining high-

quality data

Assessing thequality of valuable

information

Advantages of

organizing data ina database

Various types ofdatabases

Roles of the

database analystsand administrators


Chapter 10


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Your Interactive Guideto the Digital World

Discovering

Computers 2012

Chapter 10

Managing a Database