CS403 Highlighted Notes

Introduction to the course................................................................................................... 9 Database definitions:........................................................................................................ 10 Importance of the Databases ........................................................................................... 12 Databases and Traditional File Processing Systems....................................................... 12 Advantages of Databases ................................................................................................ 15

Difference between Data and Information........................................................................ 17 Further Advantages of Database Systems:...................................................................... 19 Cost Involved:................................................................................................................... 21 Importance of Data ........................................................................................................... 22 Levels of Data................................................................................................................... 22 Users of Database Systems:............................................................................................ 24

Database Architecture:..................................................................................................... 31 The Architecture: .............................................................................................................. 33 External View (Level, Schema or Model): ........................................................................ 35 Conceptual or Logical View:............................................................................................. 37

Internal or Physical View / Schema...................................................................... 40 Data Independence: ................................................................................................... 43 Functions of DBMS .................................................................................................... 45

Database Development Process...................................................................................... 51 Preliminary Study: ............................................................................................................ 51 Database Development Process: Approach 2 ................................................................. 54 Tools Used for Database System Development: ............................................................. 56 Data Flow Diagrams:........................................................................................................ 56 Types of DFD.................................................................................................................... 60

Detailed Data Flow Diagram:............................................................................................ 63 Data Dictionary ................................................................................................................. 64 Database Design Phase................................................................................................... 67 Data Model ....................................................................................................................... 68 Types of Data Models....................................................................................................... 68 Types of Database Design ............................................................................................... 69

Entity-Relationship Data Model ........................................................................................ 70 The Entity.......................................................................................................................... 71 Classification of entity types ............................................................................................. 74 Attribute ............................................................................................................................ 75 Types of Attributes............................................................................................................ 77 Summary: ......................................................................................................................... 79 Exercises: ......................................................................................................................... 79

Attributes........................................................................................................................... 80 The Keys........................................................................................................................... 80

Relationships .................................................................................................................... 85 Types of Relationships ..................................................................................................... 87

Roles in Relationships ...................................................................................................... 95 Dependencies................................................................................................................... 97 Enhancements in E-R Data Model: .................................................................................. 98 Super-type and Subtypes................................................................................................. 98 Summary: ......................................................................................................................... 99

Inheritance Is .................................................................................................................. 100 Super types and Subtypes ............................................................................................. 101 Specifying Constraints.................................................................................................... 103 Completeness Constraint ............................................................................................... 103 Disjointness Constraint................................................................................................... 104 Subtype Discriminator .................................................................................................... 108

Steps in the Study of system.......................................................................................... 110 Identification of Entity Types of the Examination System .............................................. 118 Relationships and Cardinalities in between Entities....................................................... 120 Conceptual Database Design......................................................................................... 122 Logical Database Design................................................................................................ 122 Conclusion...................................................................................................................... 123

Relational Data Model .................................................................................................... 125 Introduction to the Relational Data model ...................................................................... 126 Mathematical Relations .................................................................................................. 129 Database Relations ........................................................................................................ 130 Summary ........................................................................................................................ 130 Exercise:......................................................................................................................... 131

Database and Math Relations ........................................................................................ 132 Degree of a Relation....................................................................................................... 133

Mapping Relationships ................................................................................................... 140 Binary Relationships....................................................................................................... 140 Unary Relationship ......................................................................................................... 144 Data Manipulation Languages........................................................................................ 146 Relational Algebra .......................................................................................................... 147 Exercise:......................................................................................................................... 147

The Project Operator ...................................................................................................... 150

Types of Joins................................................................................................................. 157 Theta Join:...................................................................................................................... 157 Equi–Join:....................................................................................................................... 159 Natural Join:.................................................................................................................... 159

Semi Join:....................................................................................................................... 161 Relational Calculus......................................................................................................... 162 Tuple Oriented Relational Calculus:............................................................................... 162 Domain Oriented Relational Calculus: ........................................................................... 162 Normalization.................................................................................................................. 162