1. Punjab College Of
Technical Education
Presentation On:-
College Website
2. E-R Model
E-R Model: Entities.
Attributes.
Relationship.
Steps to form E-R Model: Identify Entities.
Find Relationship.
Draw rough E-R.
Fill the cardinality.
Define Primary key.
Draw key based ERD.
Identity Attributes.
Map Attributes.
Draw full attribute of ERD.
Check Result.
3. • Store Information in Systematic Manner
• Reduce the Problem of End-user
• Easy to Store an Retrieval
• Track the Information
4. Users
• Different users can access data
• Depending on their degree of expertise users
are classified in the following groups
– Naïve Users (ATM user)
– Online Users
– Application Programmers
– Sophisticated Users
– DBA
5. Entity Relationship Model
• Entity – It is anything real or abstract about which we
want to store the data .
• Relationship – It specifies the association that
exists between one or more entities.
• Attribute – It is the characteristic which is common to
all or most instances of particular entity.
6. Dependencies
What is Dependencies?
Types of Dependencies
Partial key Dependencies.
Primary key Dependencies.
Transitive key Dependencies.
Functional key Dependencies.
9. Normalization
• It is a process during which redundant relation schemas are
decomposed by breaking up their attributes in to smaller
relation schemas that possess desirable properties.
1. First N/F
2. Second N/F
3. Third N/F
4. BNC N/F
10. Normalization Form
BC N/F
Third N/F
Second N/F Eliminate
First N/F Eliminate Functional
Transitive key dependency
Removing dependency
Partial key
Eliminate dependency
Repeating
Groups
12. Relationships
• Association between entities
• Connected entities are called participants
• Operate in both directions
• Connectivity describes relationship
classification
– 1:1, 1:M, M:N
• Cardinality
– Expresses number of entity occurrences associated
with one occurrence of related entity
12
18. Keys
• Candidate Key
– A minimal set of attributes that uniquely identifies a tuple
• Primary Key
– The candidate key chosen as the identifying key of the
relation
• Alternate Key
– Candidate keys which are not primary keys
19. • Foreign Key
– An attribute (or set of attributes) in table R1 which
also occurs as the primary key of relation R2.
– R2 is called the referenced relation.
– Foreign keys are also called connection keys or
reference attributes.
