cs-1q im 2002-03 revision 21 january 2003 1 revision cs-1q im lecture 10 phil gray simon gay

1CS-1Q IM 2002-03 Revision 21 January 2003

Revision

CS-1QIM Lecture 10

Phil GraySimon Gay


The Class Test Friday 31st January, 1.30 - 2.45 pm,

Hunter Halls (East and West) Two questions: ANSWER BOTH!

one question on HCI, of similar structure to thepractice questions and past exam questions

one question on Mathematics and Information Management

30 minutes per question, + 15 minutes reading/checking time


A Word from Chris about HCI

You need to know what a mental model is.

Revise the section on Elicitation.


Overview Basic Division between

Information Management (~ 75-80%) Sets & Relations (~20-25%)


Types of Questions objective content

what is define list explain the difference between

worked examples e.g., ER diagrams, queries questions on sets & relations

critical question compare, assess explain the relationship between


Content Lecture 1: Issues in Managing Data Lecture 2: Data Modelling & ER Diagrams Lecture 3: The Relational Data Model Lecture 4: Creating Database Tables from an

ER Diagram Lectures 5-6: Sets and Relations Lecture 7: Querying Relational

Databases Lectures 8-9: SQL


Content Data, information and knowledge Databases & DBMSs

definitions layered architecture

ER Modelling what’s a model? be able to define the elements be able to produce a simple ER diagram


Content Relational Model

be able to define the elements keys constraints transforming from / comparing to ER Model

Sets & Relations based around the tutorial exercises


Content Querying Relational Databases

understand the operations be able to relate them to sets & relations

SQL know the syntax & semantics be able to write and explain simple queries


Model Answer (a)

(3 marks) A database is one or more structured sets ofpersistent data, usually held on computer and associated withsoftware to update and query the data. A database managementsystem is a suite of programs that manage databases (or aninformation system where the data may be shared by differentapplications).

Other functions:(1) multiple views of the same data(1) controlled concurrent access to data(1) management of security and integrity


Model Answer (b)

Widget Warehousestored in1N

price

description

typeidentifier identifier address

street city postcode

1 mark for entities, 1 mark for attributes, 1 mark for compositeattribute, 1 mark for relationship, 0.5 marks for cardinality,0.5 marks for total participation of widgets,1 mark for primary keys


Model Answer (b) (continued)

(2 marks) The association should be represented by includingan attribute in the Widget table to hold a foreign keyreferring to the primary key in the Warehouse table.


Model Answer (c)

(i) (1 mark) True, because stands for the empty set, and theempty set is a subset of every set.

(ii) (1 mark) True, because A is the set of all elements of U thatare greater than 2. The order of listing elements is notsignificant.

(iii) (1 mark) 3, 1


Model Answer (c) (iv)

(2 marks) 1

2

3

4

Not transitive because, for example, we have tuples<1,2> and <2,3> but not <1,3> (there are 2 other examples)

Transitive means: if xRy and yRz then xRz.

cs-1q im 2002-03 revision 21 january 2003 1 revision cs-1q im lecture 10 phil gray simon gay

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