This document discusses database systems and the database design lifecycle. It covers topics such as the difference between a database and DBMS, database schemas, ER diagrams, relationships and cardinalities. The agenda includes an active discussion on these concepts, creating a schema for a university database example, and exploring ER diagrams. The database design lifecycle involves creating ERDs, defining relationships between entities, setting attributes, and specifying cardinalities of relationships as one-to-one, one-to-many, many-to-one, or many-to-many. Examples of each type of relationship are also provided.

1. DATABASE SYSTEMS
M AHMAD ABBAS
Dept. of Computer Science
Lecture 3

2. BACKGROUND
 Remind the last lecture and answer the
following questions:
 DBMS Functions
 Difference between Database and DBMS
 What is database schema
 What are three levels of Database in Three level
architecture

3. TODAY’S AGENDA
 Before Break: Active Discussion and participation
of students on Database, DBMS Database
Schema, creating Schema on white board, RDMS,
Data
 Then we will know about Database Design Life
Cycle later after break in detail

4. CREATING SCHEMA
 You have University Databases,
 Identify its Tables, Columns, etc.
 Create Schema then

5. DISCUSSION
 So, DBM RDBMS what actually these terms are?
 Database v DBMS
 Schema and its attributes

6. DATABASE DESIGN LIFE CYCLE
 ERD
 Relationships
 Cardinalities
 Attributes

7. ENTITY RELATIONSHIP DIAGRAM
 What it is
 How it is created
 When it is created
 In Which tool it is created

8. ER
 1976 proposed by Peter Chen
 ER diagram is widely used in database design
 Represent conceptual level of a database system
 Describe things and their relationships in high level

9. BASIC CONCEPTS
 Entity set – an abstraction of similar things, e.g.
cars, students
 An entity set contains many entities
 Attributes: common properties of the entities in a
entity sets
 Relationship – specify the relations among entities
from two or more entity sets

10. AN EXAMPLE

11. RELATIONSHIP
 A relationship may be thought as a set as well
 For binary relationship, it enumerates the pairs of
entities that relate to each other
 For example, entity set M = {Mike, Jack, Tom} entity set
F = {Mary, Kate}. The relationship set married between
M and F may be {<Mike,Mary>,<Tom, Kate>}

12. RELATIONSHIP
 A relationship set is a mathematical relation among n
 2 entities, each taken from entity sets
{(e1, e2, … en) | e1  E1, e2  E2, …, en 
En}
where (e1, e2, …, en) is a relationship
 Example:
(Hayes, A-102)  depositor

13. RELATIONSHIP EXAMPLE

14. ATTRIBUTE OF A RELATIONSHIP SET

15. RELATIONSHIP
 The degree of a relationship = the number of entity
sets that participate in the relationship
 Mostly binary relationships
 Sometimes more
 Mapping cardinality of a relationship
 1 –1
 1 – many
 many – 1
 Many-many

16. ONE-ONE AND ONE-MANY

17. MANY-ONE AND MANY-MANY

18. 1- MANY

19. MANY - 1

20. MANY - MANY