CS-1Q IM Revision 21 January Revision CS-1Q IM Lecture 10 Phil Gray Simon Gay

CS-1Q IM Revision 21 January The Class Test Friday 31st January, pm, Hunter Halls (East and West) Two questions: ANSWER BOTH! one question on HCI, of similar structure to the practice questions and past exam questions one question on Mathematics and Information Management 30 minutes per question, + 15 minutes reading/checking time

CS-1Q IM Revision 21 January A Word from Chris about HCI You need to know what a mental model is. Revise the section on Elicitation.

CS-1Q IM Revision 21 January Overview Basic Division between Information Management (~ 75-80%) Sets & Relations (~20-25%)

CS-1Q IM Revision 21 January 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

CS-1Q IM Revision 21 January 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

CS-1Q IM Revision 21 January 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

CS-1Q IM Revision 21 January Content Relational Model be able to define the elements keys constraints transforming from / comparing to ER Model Sets & Relations based around the tutorial exercises

CS-1Q IM Revision 21 January 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

CS-1Q IM Revision 21 January Model Answer (a) (3 marks) A database is one or more structured sets of persistent data, usually held on computer and associated with software to update and query the data. A database management system is a suite of programs that manage databases (or an information system where the data may be shared by different applications). Other functions: (1) multiple views of the same data (1) controlled concurrent access to data (1) management of security and integrity

CS-1Q IM Revision 21 January Model Answer (b) WidgetWarehouse stored in 1 N price description typeidentifier address streetcitypostcode 1 mark for entities, 1 mark for attributes, 1 mark for composite attribute, 1 mark for relationship, 0.5 marks for cardinality, 0.5 marks for total participation of widgets, 1 mark for primary keys

CS-1Q IM Revision 21 January Model Answer (b) (continued) (2 marks) The association should be represented by including an attribute in the Widget table to hold a foreign key referring to the primary key in the Warehouse table.

CS-1Q IM Revision 21 January Model Answer (c) (i) (1 mark) True, because  stands for the empty set, and the empty set is a subset of every set. (ii) (1 mark) True, because A is the set of all elements of U that are greater than 2. The order of listing elements is not significant. (iii) (1 mark) 3, 1

CS-1Q IM Revision 21 January Model Answer (c) (iv) (2 marks) Not transitive because, for example, we have tuples and but not (there are 2 other examples) Transitive means: if xRy and yRz then xRz.