Exam (elaborations)
INF2603 EXAM PACK 2021 (SUMMARY< EXAMS< MEMO"S<ASSIGNMENTS)
- Institution
- University Of South Africa (Unisa)
- Book
- Database Systems
Exam pack for INF2603 for the year 2021
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INF2603 EXAM PACK 2021,INF2603 SUMMARY
2021
,Contents
Chapter 1: Database Systems ........................................................................................................................... 4
Types of databases ......................................................................................................................................... 4
Historical Roots: Files and File Systems ...................................................................................................... 4
Basic file terminology: ............................................................................................................................... 4
Structural and Data dependence:............................................................................................................ 5
Data Redundancy ....................................................................................................................................... 5
Database Systems .......................................................................................................................................... 5
The database system environment ......................................................................................................... 5
DBMS Functions ......................................................................................................................................... 6
Managing the DB System .......................................................................................................................... 6
Chapter 2: Data Models ..................................................................................................................................... 7
The Importance of Data Models .................................................................................................................. 7
Data Model Basic Building Blocks ................................................................................................................ 7
Business Rules ................................................................................................................................................. 7
Discovering Business Rules ....................................................................................................................... 7
The Evolution of Data Models ...................................................................................................................... 7
The Hierarchical Model ............................................................................................................................. 7
The Network Model ................................................................................................................................... 7
The Relational Model ................................................................................................................................ 7
The Entity Relationship Model ................................................................................................................. 8
The Object-Orientated (OO) model......................................................................................................... 8
Degrees of data abstraction ......................................................................................................................... 9
Chapter 3: The Relational Database Model .................................................................................................. 10
A logical view of data ................................................................................................................................... 10
Tables and their characteristics ............................................................................................................. 10
Attributes and Domains .......................................................................................................................... 10
Degree of cardinality ............................................................................................................................... 11
Keys ................................................................................................................................................................ 11
Integrity Rules ............................................................................................................................................... 12
The data dictionary and the system catalogue ........................................................................................ 12
, Relationships within the relational database........................................................................................... 13
The 1:* Relationship ................................................................................................................................ 13
The 1:1 Relationship ................................................................................................................................ 13
The *:* Relationship ................................................................................................................................ 13
Data redundancy revisited .......................................................................................................................... 14
Indexes ........................................................................................................................................................... 14
Codd’s relational database rules ................................................................................................................ 14
Chapter 5: Entity relationship (ER) modelling .............................................................................................. 16
The entity relationship (ER) model ............................................................................................................ 16
Entities ....................................................................................................................................................... 16
Attributes .................................................................................................................................................. 16
Relationships............................................................................................................................................. 18
Multiplicity ................................................................................................................................................ 18
Existence dependence............................................................................................................................. 18
Relationship strength .............................................................................................................................. 18
Weak entities ............................................................................................................................................ 19
Relationship participation....................................................................................................................... 19
Relationship degree ................................................................................................................................. 19
Recursive relationships ........................................................................................................................... 20
Composite entities ................................................................................................................................... 20
Developing an ER diagram .......................................................................................................................... 21
Database design challenges: Conflicting goals......................................................................................... 21
Chapter 6: Advanced Data Modelling ............................................................................................................ 22
The extended entity relationship model (EERM) .................................................................................... 22
Entity supertypes and subtypes ............................................................................................................. 22
Specialisation hierarchy .......................................................................................................................... 22
Inheritance ................................................................................................................................................ 22
Subtype Discriminator ............................................................................................................................. 22
Disjoint and overlapping constraints .................................................................................................... 22
Completeness constraint ........................................................................................................................ 23
Specialisation and generalisation .......................................................................................................... 23
Composition and Aggregation................................................................................................................ 23
Entity Clustering ........................................................................................................................................... 24
Entity integrity: Selecting primary keys .................................................................................................... 24
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