Informasi dan Database Pertemuan 4

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Mata Kuliah : CSS 113 , Konsep Sistem Informasi

Tahun Akademik : 2012/2013

Informasi dan Database

Pertemuan 4

Learning Outcomes :

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :

Menerangkan hubungan Teknologi Informasi dengan database yang mendukung konsep work sistem

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Outline Materi

• _{Data modeling}

• _{Database Management System}

An information architecture

• _{What information is in a system?} • _{How is the information organized?} • _{How can users get the information}

they want?

• _{Are these points independent?}

• _{How can we represent this? Do we}

need a tool?

(3)

A model for representing

information and relationships

• _{What kinds of things are important}

in this system?

• _{How are these things (entities)}

related?

• _{What information (attributes) are}

collected about these things?

(4)

Entity Relationship

Diagram

(5)

So…what do these symbols mean ?

(6)

Symbols in an ERD

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Attributes (information) about

our entities (from Alter pp. 113

)

DEPARTMENT

•Department identifer •College

•Department head

•Scheduling coordinator

COURSE

•Course number •Department

•Required of department major (y/n) •Course description

SECTION

•Section identifcation number •Semester

•Year

•Classroom •Start time •End time

•Days of week for class meetings

PROFESSOR

•Employee identifcation number •Name

•Address •Birthdate

•Ofce telephone

•Social Security number

STUDENT

•Student identifcation number •Name

•Address •Birthdate •Telephone •Gender •Ethic group

•Social Security number

OFFICE

•Ofce number •Building

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What other attributes may be

needed

• _{What needs to be added?}

• What needs to be changed?

• _{What are common attributes that}

can be used to “join” the tables?

• _{For class Thursday, have an idea}

of how you think these entities

could be improved…we are going to spend some time setting up a database

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User’s View of a

Computerized Database

• _{Types of Data}

• _{What is a Database?} • _{What is a File?}

• _{Relational Databases}

• _{Geographic Information Systems}

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Types of data…

• _{Formatted data items} • _Text

• _Images • _Audio • _Video

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What is a database?

• _{A structured collection of items}

stored, controlled and accessed through a computer based on

predefned relationships between predetermined data types.

• _{What are some examples of}

databases that you are familiar with?

• _{NOT a DBMS!}

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Files and records and

felds...

• _File

– _{A set of records}

• _Record

– _{A set of felds}

• _Field

– _{A group of characters with a}

predefned meaning • _Key

– _{A feld that uniquely identifes an}

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Relational Databases

• _{“A set of two-dimensional tables}

in which one or more key-felds in each tables are associated

with corresponding key or non-key felds in other tables.”

• _{Normalization}

– _{eliminating redundancies from}

tables in the database

• _{Typically accessed via SQL}

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Other types of databases

• _{Geographical Information}

Systems

– _{becoming quite important for}

county and local governments

– _{Locally, Orange County and the}

Town of Chapel Hill are looking for ways to integrate GIS data with

their information systems • _{Image/video databases}

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Database Management

Systems

• _{Defning the Database}

• _{Methods for Accessing Data in a}

Computer System

• _{Processing Transactions} • _{Controlling Distributed}

Databases

• _{Backup and Recovery}

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So…what is a DBMS?

• _Examples

– _Oracle – _Sybase – _Access

• _{Makes data more of an}

enterprise resource and makes programming work more

effective/effcient

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Defning the database and

Access to Data

• _{Data defnition}

– _{kept in a data dictionary}

• _{Metadata (data about data!)}

– _{Data defnition for a database is a}

schema

• _{DBMS Access}

– _{typically will be some form of}

indexed access

– _{sometimes, sequential access is}

useful

• _{less fexible}

– _{controlled by the DBMS to minimize}

complexity

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Indexed access

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Transaction processing

• _{Small section in the book, but}_very

important

– _{provides control for logical units of}

work

– _{locks resources}

– _{manages concurrency}

– _{provides queuing and prioritization}

• _{Can be in the DBMS or a separate}

transaction server

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Controlling Distributed

Databases

• _Replication

– _{decentralized storage of}

information

• _{Two-phase commit}

– _{maintain consistency}

– _{try to protect data from network or}

system failures

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Backup and recovery

• _{Backup is often neglected}

• _{Disaster recovery plans are often}

non-existent

– _{Why do you need a disaster recovery}

plan?

– _{What is in such a plan?}

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Review of things covered

so far...

• _{A model for describing information}

in a system and the relationships

– _{the ERD}

• _{What is a database?} • _{What is a DBMS?}

• _{What is a transaction processing}

system?

• _{What about backup and recovery?}

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Hands-on Lab: Building a

database

• _{Use your modifed table 4.2}

(from Alter, page 113)

• _{Create tables in Access for the}

entities

• _{Establish appropriate}

relationships

• _{Populate with sample}

information

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Text Databases and

Hypertext

• _Hypertext • _Browsers

• _{Indexes and Search Engines}

(25)

Hypertext

• _{Most common example today is}

HTML

– _H_yper_T_ext_M_arkup_L_anguage

• _{Web combines hypertext and}

multimedia to be a

“hypermedia” system

• _{Let’s look at some HTML}

– _{This may be a review for many, but}

bear with us so we can all reach a

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The HTML for our class main page

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">

<center>School of Information and Library Science University of North Carolina at Chapel Hill</center> <center>

<h2> INLS60

Information Systems Analysis and Design Fall 2000</h2></center>

<center>Tuesday/Thursday 2:00-3:15PM 307 Manning

Joel Dunn joel_dunn@unc.edu

Office - 440 W. Franklin St., Rm. 07 Phone: Office - 966-5837; Home - 968-1911

<a href="F00-Syllabus.html">Syllabus</a> / <a href="F00-Calendar.html">Calendar</a>

/ <a href="F00-Assignments.html">Assignments</a> / <a href="F00-Comm.html">Communications</a></center>

<hr ALIGN="CENTER">Course Description:

Analysis of organizational problems and how information systems can be designed to solve those problems. Application of database and interface design principles to the implementation of information systems.

Last modified 3 August, 2000

</html>

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How does the browser

ft in?

• Retrieve pages from the text databases of Web servers

• Act as today’s defacto standard

terminal for other types of database access

– _{http://bullhead.ais.unc.edu/cgi-bin/}

waisretrieve.pl?1301425xxx130395 6xxx/home/longlegs/fyfsh/log00/lo g0001d.txt:fyfsh00

• Provide vector to launch applets

• _{Provide access to servlets}

• _{Both applets & servlets are used for}

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Overview of Java

Servlets

Java Servlets

L

Name: Smith SSN: 111-22-3333

Enter

import javax.servlet.*;

class MyServlet extends GenericServlet { public void service( ServletRequest request,

ServletResponse response ) throws ServletException, IOException {

... } }

Program that runs on Web Server, Registered with Web Server No graphical User Interface (HTML)

Less resource-intensive than CGI programs (load once, run many) Portable to other Web Servers, positioning for future EJBs

Part of JDK 1.1 as a Standard Java Extension API (GenericServlet, HTTPServlet class)

Can be programmed to access existing applications, dist. objects, etc. Can be used to improve end-to-end performance

Can be used to address firewall concern

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Let’s review the basic

model of

browser/server

interaction

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Indexes and search

engines

• _{In the web context, what is an}

index?

• _{What does a search engine do?}

– _{How is a search engine like a DBMS?}

• _{How has the pervasiveness of}

hypertext and web-based searching changed the way we deal with

collections of information?

• _{What are your favorite search}

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Evaluating Information

Used in Business

Processes

• _{Information Quality}

• _{Information Accessibility} • _{Information Presentation} • _{Information Security}

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Information quality

INFORMATION QUALITY

•ACCURACY

•PRECISION

•COMPLETENESS

•AGE

•TIMELINESS

•SOURCE

•What are some examples of these qualities?

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Information accessibility,

presentation and security

INFORMATION ACCESSIBILITY

•AVAILABILITY •ADMISSIBILITY

INFORMATION PRESENTATION

•LEVEL OF SUMMARIZATION •FORMAT

INFORMATION SECURITY

•ACCESS RESTRICTION •ENCRYPTION

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Let’s think about a

database and evaluate it

based on these criteria

• _{What about your academic}

record, your history of courses taken and grades received here at UNC?

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Models as Components of

Information Systems

• _{Mental Models and Mathematical}

Models

• _{What-if Questions}

Models…

• _{A part of the decision making}

process

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A mental model…how

you think things work...

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Mathematical model

• _{Series of equations/algorithms}

that describe relationships between variables

• _{Is often an instantiation of a}

mental model in an information system to apply data to solve a problem

Closing

• _{Data modeling}

• _DBMS

• _{Backup & Recovery}

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Closing

• _{Data modeling}

• _DBMS

• _{Backup & Recovery}

========== thanks 4 your attention =========