TOPIC: Types of Attributes and Types of Relation

2. Entities are represented by means of their properties is called attributes.
Attributes are characteristics of an entity
name
Age
Roll no Date of Birth
Phone No.
Bye the help of the attributes or properties we can say, he is a student.
Entity: entity maybe an object with physical existance. Example : person,car,house
or
entity maybe an object with conceptual existance. Example : company, job, universities

3. Atrribute
Simple attribute
Composite atrribute
Derived atrribute
Single Valued attribute
Multi valued attribute

4. Simple attributes are atomic values, which cannot be
divided further.
For example:
Age
Phone No.

5. Composite attributes can be divided into smaller sub
parts.
For example:
Name
Last NameFirst Name
Address
cityHouse no

6. Derived attributes are the attributes that do not exist in
the physical database, but their values are derived from
other attributes present in the database.
For example:
age
Date of Birth
Bye the help of date of birth attribute a person age can be calculated
An attribute that cannot be
derived from another
attribute is known as stored
attribute.

7. An Attribute that has only single value for an entity is
known as single value attributed.
For example:
age
Date of birth

8. An attribute that can have multiple values for an entity is
known as multivalue attribute .
For example:
email Phone no
A Student can have more than one phone no..
A Student can have more than one email address..

9. Age
Employee id
Date of Birth
Phone No.
diagrammatic representation of entity attribute relations
Name
Last Name
First Name

10. Relation
One to One
One to Many
Many to One
Many to Many

11. One entity from entity set A can be associated with at most one
entity of entity set B and vice versa
diagram
table

12. One entity from entity set A can be associated with more than one
entities of entity set B however an entity from entity set B, can be
associated with at most one entity.
diagram
table

13. More than one entities from entity set A can be associated with
at most one entity of entity set B, however an entity from
entity set B can be associated with more than one entity from
entity set A.
diagram
table

14. diagram
One entity from A can be associated with more than one
entity from B and vice versa.

15. Here is the graphical represenation of all relations:
Table - A Table - B
One to One
Table - A Table - B
One to Many
Table - A Table - B
Many to One
Table - A Table - B
Many to Many