Introduction to ERDs



An Introduction to Entity Relationship Diagrams (ERDs)

A Practical Guide for Beginners

Written by: Robin Beaumont e-mail: robin@organplayers.co.uk

Date last updated: 31/12/2002 15:37

Version: 1

How this document should be used:

This document has been designed to be suitable for web based and face-to-face teaching. The text has been made to be as interactive as possible with exercises, Multiple Choice Questions (MCQs) and web based exercises.

If you are using this document as part of a web-based course you are urged to use the online discussion board to discuss the issues raised in this document and share your solutions with other students.

Who this document is aimed at:

This document is aimed for two types of people:

( Those who wish to become involved in database development but are not interested in the nuts

and bolts of programming, such people are commonly called domain experts and act a bridges

between a professional group (e.g. medics, Solicitors etc) to which they belong and IT experts.

( As an introduction for those just beginning professional computer science courses

I hope you enjoy working through this document.

Robin Beaumont

Contents

1. Before you start 4

1.1 Prerequisites 4

1.2 Required Resources 4

2. Learning Outcomes 5

2.1.1 5

2.1.2 Subsection 3 - Aspects of the Internet 5

2.2 Panopticon 5

2.2.1 Jeremy Bentham and the Panopticon 5

Task: Reading m08-03-43-38 6

Task: Communication issues m08-03-43-39 6

Task: MCQs m08-03-44-40 7

2.3 Summary 10

3. Introduction 11

4. Summary 12

5. References 12

6. Links 12

7. Appendix A Relationship Terminology 13

Before you start

1 Prerequisites

This document assumes that you have the following knowledge and skills:

Skills:

That you have used the following features of a Database Management System (DBMS) such as Access or Paradox:

• Create Tables

• Create Relationships (and therefore known about the relationship window)

• Created simple Queries in the query design window

• Created a simple form

Knowledge:

You should also be able to describe what the following concepts mean:

• Tables, indexes and Fields

• Relationships (not a detailed description)

• Forms

• Queries

If you have done the ECDL (European Computer Driving Licence) you will have covered these topics. If not I recommend that you do so now. You can take the ECDL either at a local college (in the UK) or as a distance Learning course. There are also some very good books guiding you through the ECDL.

2 Required Resources

You need the following resources to work through this document:

• Download the DeZign CASE tool (1.33 Mbytes) from the DeZign website. If you are working through this document as part of the Diploma in Medical Informatics course (RCSEd) or the MSc in Healthcare Informatics course (Bath + RCSEd) please look at the course discussion board for details.

• Read the tutorial to DeZign (14 pages, 0.5 Mbyte). You can download this also from the DeZign website. If you are working through this document as part of the Diploma in Medical Informatics course (RCSEd) or the MSc in Healthcare Informatics course (Bath + RCSEd) please look at the course discussion board for details.

• The “Scenarios for practicing modelling techniques” handout available

• from and follow the links

Learning Outcomes

This document aims to provide you with the following skills and information. After you have completed it you should come back to these points, ticking off those you feel happy with.

1

2 Subsection 3 - Aspects of the Internet

|Be aware of the Panoption concept and Zuboffs adaption of it to the Internet |θ |

|Be able to provide a short description of what Technological Determinism is |θ |

|Be aware of the traditional management strategies facilitated by IT |θ |

|Be aware of the Global Village concept |θ |

|Be aware of the cultural Overlay concept |θ |

|Be able to describe various types of Virtual Reality |θ |

|Be aware of the issues related to Teleworking and how it might affect you |θ |

|Be aware of the general affects e-mail has upon communication and yourselves |θ |

|Be aware of the Cyberbody and Cyberpunk concepts |θ |

|Be aware of the Cyborg concept |θ |

|Be aware of Sven Birkerts work concerning traditional Reading, writing and the Internet |θ |

2 Panopticon

Now we will look at the human communication aspects of the Internet along with some of the interesting findings concerning email.

This subsection consists of you reading two PDF documents, visiting a series of websites and then answering the MCQs concerning them.

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1 Jeremy Bentham and the Panopticon

Go to the following links to see what a Panopticon looks like and learn a little about it.

The original picture of the Panopticon:



To discover where panopticons were built see:



Another picture of a Panopticon is at:



or:



For a bit of light relief, look at the contemporary Panopticon in Manchester, UK:



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The following links are given for reference purposes. You do not need to go to them for the purpose of passing the course!

For a detailed article about the Panopticon see:



Jeremy Bentham's requested in his will to have his body on display you can see it at:



There is also a Jeremy Bentham project at University College London:



For a list of Jeremy Bentham websites see:



Details of manuscripts and another pictures of Panopticon can be found at:



Additional hyperlinks taken from (again for reference only):



University of Tennessee at Martin

Entry from the Internet Encyclopedia of Philosophy. After a discussion of Bentham's life and times, this entry treats his method, view of human nature, moral philosophy, and political philosophy. It also includes a bibliography of his works and a select bibliography of secondary sources.

The Pioneers: The Earliest Writers in English on Homosexuality

Summaries of books and articles on homosexuality dating from the 1700s. Includes the full text of Jeremy Bentham's "Offences Against One's Self: Paederasty" (c. 1785).



University of Tennessee at Martin

Chapters 1 through 4 of this classic philosophical text by Jeremy Bentham, in which he provides theoretical foundations of a system of law and government.

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Task: Reading m08-03-43-38

45 minutes

Now please read sections 1 to 4 (page 6) of:

Social issues one:

Carry out the five exercises mentioned in sections 1 to 4 of the above text.

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Task: Communication issues m08-03-43-39

45 minutes

We will now look in more detail at various communications issues and the Internet. Please read all of:

Social issues 3:



Please carry out the exercises mentioned in the above text.

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Task: MCQs m08-03-44-40

20 minutes

1. What was Jeremy Bentham's Panopticon?

a. A technique for rehabilitating offenders

b. A technique for punishing offenders

c. An architectural design enabling the observation of prisoners

d. An architectural design enabling the minimal movement of prisoners

e. An architectural design providing a total institution for prisoners

2. Who was the person who applied the Panopticon concept to computer networks?

a. Marshall McLuhan

b. Toffler

c. Zuboff

d. Kelly

e. Kling

3. Which of the following provides the best description of what technological determinism is?

a. A Technology creating a need

b. A problem waiting for the technology

c. A mutual dependency between a problem and a technological development

d. A barrier beyond which technology cannot progress

e. A technology being inappropriately used

4. Child 1987 suggests four managerial strategies that are facilitated by technology. Which of the following is one of them?

a. Enhanced training opportunities

b. Greater role definition

c. Organisational democratisation

d. De-skilling

e. Developing ‘the learning organisation’

5. What do the letters EPOS stand for?

a. Electronic Point of Sale Service

b. Emergency Point of Service Systems

c. Electronic Point of Surgery Systems

d. Emergency Point of Surgery Systems

e. Electronic Point of Sale Systems

6. What is Marshall McLuhan most famous for?

a. The beehive concept

b. The global village concept

c. The good village concept

d. The global van concept

e. The global varangian concept

7. Which of the following best describes the concept of ‘cultural overlay’?

a. The splitting in society between those who have Web access and those who do not

b. The splitting in society between those who are web educated and those who are not

c. The splitting in society between those who were brought up with the Web and those who weren’t

d. The splitting in society between those who prefer cultural interaction to those who prefer web based interaction

e. The splitting in society between those who use the web for cultural experiences and those who use it for business

8. In 1992 Langdon Winner wrote an article about Teleworking. What was its title?

a. Electronic office: Pleasuredom or Abyss

b. Electronic office: playpen or prison

c. Electronic office: performance and pleasure

d. Electronic office: playpen and its tools

e. Electronic office: playpen of the future

9. Both Forester and Olson published findings concerning Teleworking in 1989. What was the general tone of their findings?

a. Generally decreased worker satisfaction and manager satisfaction

b. Generally increased worker satisfaction and manager satisfaction

c. Generally increased worker satisfaction and decreased manager satisfaction

d. Generally decreased worker satisfaction and increased manager satisfaction

e. No difference in satisfaction in either worker or manager

10. Generally, email:

a. Increases inhibition

b. Decreases inhibition

c. Has no effect upon communication

d. Only increases inhibition in females

e. Only decreases inhibition in males

11. What are datagloves?

a. Gloves to wear to protect you from unpleasant data

b. Gloves that provide sensations via computer control

c. Gloves that can mimic certain sensations due to some form of electronic control

d. Gloves that prevent any sensory input to the hands

12. What is a cyberbody?

a. A fictitious persona adopted in a virtual reality environment

b. A real change in persona brought about by the use of virtual reality

c. A character in a sci fi movie

d. A particular state of mind

e. A made up word

13. Generally, in academic circles, which of the following is considered a true statement about the cyborg condition:

a. It can be argued that this condition already exists to a limited extent

b. The cyborg condition will become the norm

c. The cyborg condition will be replaced by complete mechanisation

d. The cyborg is a myth

e. The cyborg has no academic credence

14. Sven Birkert’s 1994 book The Gutenberg Elegies describes his teaching of literature to students. Which of the following most clearly represents his findings?

a. They had difficulty with any deviations from the plot as well as literary devices such as irony.

b. They had difficulty slowing down enough to concentrate and with any deviations from the plot as well as literary devices such as irony.

c. They had difficulty slowing down enough to concentrate and with any deviations from the plot as well as the paper layout and literary devices such as irony.

d. They had difficulty slowing down enough to concentrate and with any deviations from the plot.

e. They had difficulty keeping up enough to concentrate and with any deviations from the plot as well as literary devices such as irony.

15. Which of the following does Sven Birkert see as a problem resulting from the use of the Web?

a. Reduced attention span

b. Less opportunity to gain knowledge

c. Reduction in vocabulary

d. Reduction in factual knowledge

e. Less opportunity to reflect on reading experiences

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3 Summary

This is left as an exercise for you.

Introduction

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Summary

This document has introduced you to a number of new concepts and provided you with the skills to use them effectively to produce ERDs. You have seen how to define and refine a set of entity types for a given scenario. You have also considered in detail the various types of relationship that can exist between entity types.

The CASE tool concept has been introduced to you by way of a practical tutorial as well as seeing what a number of suppliers have to offer.

I would now recommend that you return to the learning outcomes at the beginning of the document and see how much you have learnt!

References

Carter John 2000 Database design & programming with Access, SQL and visual basic McGraw Hill

Carter John 1995 The Relational Database. Chapman and Hall [An excellent introductory book]

Date C J. 1995 (6th ed.) An introduction to database systems. Addison-Wesley.

Elmasri R Navathe S B 1989 Fundamentals of database systems. Benjamin Cummings Wokingham UK.

Everest G 1986 Database management. McGraw-Hill. London.

Finkelstein Clive 1989 An introduction to information engineering. Addision-Wesley. Wokingham UK.

Finkelstein Clive 1992 Information engineering. Addision-Wesley. Wokingham UK.

Hernandez M J 1997 Database design for mere Mortals. Addison - Wesley

Martin James 1981 An end user’s guide to data base. Prentice Hall [ISBN 0-13-277129-2]

Reingruber Michael C. Gregory William W 1994 The Data Modelling Handbook John Wiley & Sons Chichester

Rumbaugh J Blaha M Premerlani W et al 1991 Object-Oriented Modelling and design. Prentice Hall.

Links

University of Texas data modelling notes:



Links to database articles (applied information science web site):



Additional ones for you to add:

Appendix A Relationship Terminology

The following table is taken from Carter 1995 p40. Different writers use different words to describe the minimum and maximum constraint on a relationship; the synonyms are listed below. I have tried to avoid using most of the terms in this document to avoid confusion. I tend to refer to relationships as being “optional” (where the minimum number of participants is zero) or “mandatory” (where the minimum is one).

|Source (writer) |Number of entities in relationship |Minimum number of participants |Maximum number of participants |

|Date | | |Degree |

|IEW | |Optionality |Cardinality |

|D.C.C | |Optionality |Degree |

|Ashworth | | |Degree |

|Eva | |Optionality |Cardinality and degree |

|Kroenke |Degree |Minimal Cardinality |Maximal Cardinality |

|Bamford | | |Degree |

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End of document

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Cardinality?

Optionality?

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