Transcript information accessibility

Matakuliah
Tahun
Versi
: H0472 / Konsep Sistem Informasi
: 2006
:1
Pertemuan 4
Informasi dan Database
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menerangkan hubungan Teknologi
Informasi dengan database yang
mendukung konsep work sistem
2
Outline Materi
• Data modeling
• Database Management System
3
Data Modeling: Documenting
Information Architecture
• Entity-Relationship Diagrams
• Identifying the Data in Information
Systems
4
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?
5
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?
6
Entity Relationship Diagram
7
So…what do these symbols
mean?
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Symbols in an ERD
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Attributes (information) about
our entities (from Alter pp.
113)
PROFESSOR
DEPARTMENT
•Department identifier
•College
•Department head
•Scheduling coordinator
COURSE
•Course number
•Department
•Required of department major (y/n)
•Course description
SECTION
•Section identification number
•Semester
•Year
•Classroom
•Start time
•End time
•Days of week for class meetings
•Employee identification number
•Name
•Address
•Birthdate
•Office telephone
•Social Security number
STUDENT
•Student identification number
•Name
•Address
•Birthdate
•Telephone
•Gender
•Ethic group
•Social Security number
OFFICE
•Office number
•Building
•Telephone extension
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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
11
User’s View of a
Computerized Database
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•
•
•
Types of Data
What is a Database?
What is a File?
Relational Databases
Geographic Information Systems
12
Types of data…
•
•
•
•
•
Formatted data items
Text
Images
Audio
Video
13
What is a database?
• A structured collection of items stored,
controlled and accessed through a
computer based on predefined
relationships between predetermined data
types.
• What are some examples of databases
that you are familiar with?
• NOT a DBMS!
14
Files and records and fields...
• File
– A set of records
• Record
– A set of fields
• Field
– A group of characters with a predefined
meaning
• Key
– A field that uniquely identifies an entity
15
Relational Databases
• “A set of two-dimensional tables in which
one or more key-fields in each tables are
associated with corresponding key or nonkey fields in other tables.”
• Normalization
– eliminating redundancies from tables in the
database
• Typically accessed via SQL
16
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
17
Database Management
Systems
• Defining the Database
• Methods for Accessing Data in a
Computer System
• Processing Transactions
• Controlling Distributed Databases
• Backup and Recovery
18
So…what is a DBMS?
• Examples
– Oracle
– Sybase
– Access
• Makes data more of an enterprise
resource and makes programming work
more effective/efficient
19
Defining the database and
Access to Data
• Data definition
– kept in a data dictionary
• Metadata (data about data!)
– Data definition for a database is a schema
• DBMS Access
– typically will be some form of indexed access
– sometimes, sequential access is useful
• less flexible
– controlled by the DBMS to minimize complexity
20
Indexed access
21
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
22
Controlling Distributed
Databases
• Replication
– decentralized storage of information
• Two-phase commit
– maintain consistency
– try to protect data from network or system
failures
23
Backup and recovery
• Backup is often neglected
• Disaster recovery plans are often nonexistent
– Why do you need a disaster recovery plan?
– What is in such a plan?
24
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?
25
Hands-on Lab: Building a
database
• Use your modified table 4.2 (from Alter,
page 113)
• Create tables in Access for the entities
• Establish appropriate relationships
• Populate with sample information
26
Text Databases and Hypertext
• Hypertext
• Browsers
• Indexes and Search Engines
27
Hypertext
• Most common example today is HTML
– HyperText Markup Language
• 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 common level of
understanding
28
The HTML for our class main
page
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="GENERATOR" content="Mozilla/4.7 [en] (Win98; I) [Netscape]">
<meta name="Author" content="Joel Dunn">
<title>INLS60, Fall 2000</title>
</head>
<body bgcolor="#FFFFFF">
<center>School of Information and Library Science
<br>University of North Carolina at Chapel Hill</center>
<center>
<h2>
INLS60<br>
Information Systems Analysis and Design<br>
Fall 2000</h2></center>
<center>Tuesday/Thursday 2:00-3:15PM
<br>307 Manning
<br>Joel Dunn
<br>[email protected]
<br>Office - 440 W. Franklin St., Rm. 07
<br>Phone: Office - 966-5837; Home - 968-1911
<p><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>
<p>
<hr ALIGN="CENTER"><b>Course Description:</b>
<p>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.
<p>
<hr ALIGN="CENTER">
<p><i>Last modified 3 August, 2000</i>
<br><i><a href="mailto:[email protected]">Joel Dunn</a></i>
</body>
</html>
29
How does the browser fit 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/cgibin/waisretrieve.pl?1301425xxx1303956xxx/home/longlegs/flyfish/log00/
log0001d.txt:flyfish00
• Provide vector to launch applets
• Provide access to servlets
• Both applets & servlets are used for data access
30
Overview of Java Servlets
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31
Let’s review the basic model
of browser/server interaction
32
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 engines,
and why?
33
Evaluating Information Used
in Business Processes
•
•
•
•
Information Quality
Information Accessibility
Information Presentation
Information Security
34
Information quality
INFORMATION QUALITY
•ACCURACY
•PRECISION
•COMPLETENESS
•AGE
•TIMELINESS
•SOURCE
•What are some examples of
these qualities?
35
Information accessibility,
presentation and security
INFORMATION ACCESSIBILITY
•AVAILABILITY
•ADMISSIBILITY
INFORMATION PRESENTATION
•LEVEL OF SUMMARIZATION
•FORMAT
INFORMATION SECURITY
•ACCESS RESTRICTION
•ENCRYPTION
36
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?
37
Models as Components of
Information Systems
• Mental Models and Mathematical Models
• What-if Questions
38
Models…
• A part of the decision making process
39
A mental model…how you
think things work...
40
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
41
Closing
• Data modeling
• DBMS
• Backup & Recovery
42