2. Information and Databases

3. Chapter Outline 4 Data Modeling: Documenting Information Architecture 4 User’s View of a Computerized Database 4 Database Management Systems 4 Text Databases and Hypertext 4 Evaluating Information Used in Business Processes 4 Models as Components of Information Systems

4. Data Modeling: Documenting Information Architecture 4 Entity-Relationship Diagrams 4 Identifying the Data in Information Systems

5. An information architecture 4 What information is in a system? 4 How is the information organized? 4 How can users get the information they want? 4 Are these points independent? 4 How can we represent this? Do we need a tool?

6. A model for representing information and relationships 4 What kinds of things are important in this system? 4 How are these things (entities) related? 4 What information (attributes) are collected about these things?

7. Entity Relationship Diagram

8. So…what do these symbols mean?

9. Symbols in an ERD

10. 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

11. What other attributes may be needed 4 What needs to be added? 4 What needs to be changed? 4 What are common attributes that can be used to “join” the tables? 4 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

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

13. Types of data… 4 Formatted data items 4 Text 4 Images 4 Audio 4 Video

14. What is a database? 4 A structured collection of items stored, controlled and accessed through a computer based on predefined relationships between predetermined data types. 4 What are some examples of databases that you are familiar with? 4 NOT a DBMS!

15. Files and records and fields... 4 File –A set of records 4 Record –A set of fields 4 Field –A group of characters with a predefined meaning 4 Key –A field that uniquely identifies an entity

16. Relational Databases 4 “A set of two-dimensional tables in which one or more key-fields in each tables are associated with corresponding key or non- key fields in other tables.” 4 Normalization –eliminating redundancies from tables in the database 4 Typically accessed via SQL

17. Other types of databases 4 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 4 Image/video databases Image/video databases

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

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

20. Defining the database and Access to Data 4 Data definition –kept in a data dictionary Metadata (data about data!) –Data definition for a database is a schema 4 DBMS Access –typically will be some form of indexed access –sometimes, sequential access is useful less flexible –controlled by the DBMS to minimize complexity

21. Indexed access

22. Transaction processing 4 Small section in the book, but very important –provides control for logical units of work –locks resources –manages concurrency –provides queuing and prioritization 4 Can be in the DBMS or a separate transaction server

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

24. Backup and recovery 4 Backup is often neglected 4 Disaster recovery plans are often non- existent –Why do you need a disaster recovery plan? –What is in such a plan?

25. Review of things covered so far... 4 A model for describing information in a system and the relationships –the ERD 4 What is a database? 4 What is a DBMS? 4 What is a transaction processing system? 4 What about backup and recovery?

26. Hands-on Lab: Building a database 4 Use your modified table 4.2 (from Alter, page 113) 4 Create tables in Access for the entities 4 Establish appropriate relationships 4 Populate with sample information

27. Text Databases and Hypertext 4 Hypertext 4 Browsers 4 Indexes and Search Engines

28. Hypertext 4 Most common example today is HTML –HyperText Markup Language 4 Web combines hypertext and multimedia to be a “hypermedia” system 4 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

29. The HTML for our class main page INLS60, Fall 2000 School of Information and Library Science University of North Carolina at Chapel Hill INLS60 Information Systems Analysis and Design Fall 2000 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 Syllabus / Calendar / Assignments / Communications 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 Joel Dunn

30. How does the browser fit in? 4 Retrieve pages from the text databases of Web servers 4 Act as today’s defacto standard terminal for other types of database access –http://bullhead.ais.unc.edu/cgi- bin/waisretrieve.pl?1301425xxx1303956xxx/home/longlegs/flyfish/log00/ log0001d.txt:flyfish00http://bullhead.ais.unc.edu/cgi- bin/waisretrieve.pl?1301425xxx1303956xxx/home/longlegs/flyfish/log00/ log0001d.txt:flyfish00 4 Provide vector to launch applets 4 Provide access to servlets 4 Both applets & servlets are used for data access

31. Overview of Java Servlets

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

33. Indexes and search engines 4 In the web context, what is an index? 4 What does a search engine do? –How is a search engine like a DBMS? 4 How has the pervasiveness of hypertext and web-based searching changed the way we deal with collections of information? 4 What are your favorite search engines, and why?

34. Evaluating Information Used in Business Processes 4 Information Quality 4 Information Accessibility 4 Information Presentation 4 Information Security

35. Information quality INFORMATION QUALITY ACCURACY PRECISION COMPLETENESS AGE TIMELINESS SOURCE What are some examples of these qualities?

36. Information accessibility, presentation and security INFORMATION ACCESSIBILITY AVAILABILITY ADMISSIBILITY INFORMATION PRESENTATION LEVEL OF SUMMARIZATION FORMAT INFORMATION SECURITY ACCESS RESTRICTION ENCRYPTION

37. Let’s think about a database and evaluate it based on these criteria 4 What about your academic record, your history of courses taken and grades received here at UNC?

38. Models as Components of Information Systems 4 Mental Models and Mathematical Models 4 What-if Questions

39. Models… 4 A part of the decision making process

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

41. Mathematical model 4 Series of equations/algorithms that describe relationships between variables 4 Is often an instantiation of a mental model in an information system to apply data to solve a problem

42. What-if Questions 4 Enabled by mathematical models 4 How things could operate given a change in circumstances 4 Discussion item… –how might we try to build a model to examine the impact of dramatically increased enrollment at UNC over the next 10 years? What elements would we put in our model; what would we exclude?