Informasi dan Database Pertemuan 4

  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

  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?

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?

  Entity Relationship Diagram

  So…what do these symbols mean ?

  Symbols in an ERD

  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}

  

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}

  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

  

User’s View of a

Computerized Database

• Types of Data • What is a Database?
• What is a File?
• Relational Databases • Geographic Information Systems

Types of data…

• Formatted data items
• Text • Images • Audio • Video

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!

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

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

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

  Database Management

Systems

• Defning the Database • Methods for Accessing Data in a

  Computer System

• Processing Transactions • Controlling Distributed

  Databases

• Backup and Recovery

So…what is a DBMS?

• Examples
• – Oracle – Sybase – Access
• Makes data more of an

  enterprise resource and makes programming work more effective/effcient

  

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

  Indexed access

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

  

Controlling Distributed

Databases

• Replication
• – decentralized storage of

  information

• Two-phase commit
• – maintain consistency

• – try to protect data from network or

  system failures

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?

  

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?

  

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

  Text Databases and Hypertext

• Hypertext • Browsers • Indexes and Search Engines

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

  The HTML for our class main page _{<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> </head> <title>INLS60, Fall 2000</title> <meta name="Author" content="Joel Dunn"> <meta name="GENERATOR" content="Mozilla/4.7 [en] (Win98; I) [Netscape]"> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">} <head> _{<center>School of Information and Library Science} <body bgcolor="#FFFFFF"> _{<center> <br>University of North Carolina at Chapel Hill</center> <center>Tuesday/Thursday 2:00-3:15PM Fall 2000</h2></center> Information Systems Analysis and Design<br> INLS60<br>} <h2> _{<br>Phone: Office - 966-5837; Home - 968-1911 <br>Office - 440 W. Franklin St., Rm. 07 <br>joel_dunn@unc.edu <br>Joel Dunn <p><a href="F00-Syllabus.html">Syllabus</a> / <a href="F00-Calendar.html">Calendar</a>} <br>307 Manning _{be designed to solve those problems. Application of database and interface <p>Analysis of organizational problems and how information systems can <hr ALIGN="CENTER"><b>Course Description:</b> <p>} / <a href="F00-Assignments.html">Assignments</a> / <a href="F00-Comm.html">Communications</a></center> _{</body> <br><i><a href="mailto:joel_dunn@unc.edu">Joel Dunn</a></i> <p><i>Last modified 3 August, 2000</i> <hr ALIGN="CENTER"> <p>} design principles to the implementation of information systems.

  </html>

  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

• –
• Provide vector to launch applets
• Provide access to servlets

  Overview of Java

Servlets Java Servlets

  L ^{M /} _W ^{P L M /} _W Web _{Server Client} ^{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)}

  Let’s review the basic model of browser/server interaction

  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

  Evaluating Information Used in Business Processes

• Information Quality • Information Accessibility • Information Presentation • Information Security

Information quality

• _•ACCURACY
>_{•COMPLETENESS} •PRECISION _{•SOURCE •TIMELINESS} •AGE
• What are some examples of these qualities?

Information accessibility, presentation and security

• _{•AVAILABILITY}
• ADMISSIBILITY _{•LEVEL OF SUMMARIZATION}
• FORMAT _{•ACCESS RESTRICTION}

  

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?

  

Models as Components of

Information Systems

• Mental Models and Mathematical

  Models

• What-if Questions

Models…

• A part of the decision making

  process

  A mental model…how you think things work...

Mathematical model

• Series of equations/algorithms

  that describe relationships Closing between variables

• Is often an instantiation of a
• Data modeling

  mental model in an information

• DBMS

  system to apply data to solve a problem

• Backup & Recovery

Closing

• Data modeling
• DBMS
• Backup & Recovery

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