CS403 Handouts

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