Mata Kuliah Tahun Akademik CSS 113 Konsep Sistem

Mata Kuliah Tahun Akademik : CSS 113 , Konsep Sistem Informasi : 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 4 -1 sistem

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? 4 -2

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 -3

Entity Relationship Diagram 4 -4

So…what do these symbols mean ? 4 -5

Symbols in an ERD 4 -6

Attributes (information) about our entities (from Alter pp. 113) 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 PROFESSOR • 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 4 -7

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 4 -8

User’s View of a Computerized Database • • • Types of Data What is a Database? What is a File? Relational Databases Geographic Information Systems 4 -9

Types of data… • • • Formatted data items Text Images Audio Video 4 -10

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! 4 -11

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 4 -12

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 4 -13

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 4 -14

Database Management Systems • Defining the Database • Methods for Accessing Data in a Computer System • Processing Transactions • Controlling Distributed Databases • Backup and Recovery 4 -15

So…what is a DBMS? • Examples – Oracle – Sybase – Access • Makes data more of an enterprise resource and makes programming work more effective/efficient 4 -16

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 4 -17

Indexed access 4 -18

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 4 -19

Controlling Distributed Databases • Replication – decentralized storage of information • Two-phase commit – maintain consistency – try to protect data from network or system failures 4 -20

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? 4 -21

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? 4 -22

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 4 -23

Text Databases and Hypertext • Browsers • Indexes and Search Engines 4 -24

Hypertext • Most common example today is HTML – Hyper. Text 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 4 -25

The HTML for our class main page <!doctype html public "-//w 3 c//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] (Win 98; I) [Netscape]"> <meta name="Author" content="Joel Dunn"> <title>INLS 60, Fall 2000</title> </head> <body bgcolor="#FFFFFF"> <center>School of Information and Library Science University of North Carolina at Chapel Hill</center> <h 2> INLS 60 Information Systems Analysis and Design Fall 2000</h 2></center> <center>Tuesday/Thursday 2: 00 -3: 15 PM 307 Manning Joel Dunn joel_dunn@unc. edu Office - 440 W. Franklin St. , Rm. 07 Phone: Office - 966 -5837; Home - 968 -1911 <p><a href="F 00 -Syllabus. html">Syllabus</a> / <a href="F 00 -Calendar. html">Calendar</a> / <a href="F 00 -Assignments. html">Assignments</a> / <a href="F 00 -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> <i><a href="mailto: joel_dunn@unc. edu">Joel Dunn</a></i> </body> </html> 4 -26

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? 1301425 xxx 1303956 xxx/ho me/longlegs/flyfish/log 0001 d. txt: flyfish 00 • Provide vector to launch applets • Provide access to servlets • Both applets & servlets are used for data access 4 -27

Overview of Java Servlets 4 -28

Let’s review the basic model of browser/server interaction 4 -29

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? 4 -30

Evaluating Information Used in Business Processes • • Information Quality Information Accessibility Information Presentation Information Security 4 -31

Information quality INFORMATION QUALITY • ACCURACY • PRECISION • COMPLETENESS • AGE • TIMELINESS • SOURCE • What are some examples of these qualities? 4 -32

Information accessibility, presentation and security INFORMATION ACCESSIBILITY • AVAILABILITY • ADMISSIBILITY INFORMATION PRESENTATION • LEVEL OF SUMMARIZATION • FORMAT INFORMATION SECURITY • ACCESS RESTRICTION • ENCRYPTION 4 -33

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? 4 -34

Models as Components of Information Systems • Mental Models and Mathematical Models • What-if Questions Models… • A part of the decision making process 4 -35

A mental model…how you think things work. . . 4 -36

Mathematical model • Series of equations/algorithms that describe relationships between variables Closing • Is often an instantiation of a mental model in an information system to apply data to solve a • problem Data modeling • DBMS • Backup & Recovery 4 -37

Closing • Data modeling • DBMS • Backup & Recovery ===== thanks 4 your attention ===== 4 -38