these slides include database design by entity and their attribute.

1. Unit -2
DATABASE DESIGN (ENTITY (OBJECT), ENTITY SET, ENTITY TYPE -
PART 3
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2. Database Design (Attributes)
Attributes
Each entity is described by a set of attributes
(e.g., Employee = (Name, Address, Birthdate (Age), Salary).
Each attribute has a name, and is associated with an entity and a
domain of legal values. However, the information about attribute
domain is not presented on the Entity Relationship Diagram.
In the entity relationship diagram, shown in Figure, each attribute is
represented by an oval with a name inside.
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3. Database Design (Attributes)
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Employee
Name Salary Birthdate Address

4. Database Design (Attributes)
Types of Attributes
There are a few types of attributes you need to be familiar with.
Some of these are to be left as is, but some need to be adjusted to
facilitate representation in the relational model. This first section will
discuss the types of attributes.
◦ Simple Attributes
◦ Composite Attributes
◦ Multivalued Attributes
◦ Derived Attributes
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5. Database Design
(Attributes)
Simple attributes
Simple attributes are
those drawn from the
atomic value domains;
they are also called
single-valued attributes.
In the COMPANY
database, an example of
this would be:
Name = {Ram} ;
Salary = {4141}
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Employee
Name Salary Birthdate Address
Simple Attributes

6. Database Design
(Attributes)
Composite attributes
are those that consist
of a hierarchy of
attributes. Using our
database example,
and shown in Figure
Address may consist
of Number, Lane and
Area. So this would be
written as →
Address = {A - 11 +
‘Lane 3’ + ‘Shatabdi
Puram, Gwalior’}
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Employee
Name Address Birthdate Salary
Number Lane Area
Composite Attributes

7. Database Design
(Attributes)
Multivalued attributes
Multivalued attributes
are attributes that have
a set of values for each
entity. An example of a
multivalued attribute
from the COMPANY
database, as seen in
Figure, are the degrees
of an employee: BSc,
MIT, PhD.
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Employee
Degree
Name Address Birthdate
Salary

8. Database Design
(Attributes)
Derived attributes
Derived attributes are
attributes that contain
values calculated from
other attributes. An
example of this can be
seen in Figure. Age can
be derived from the
attribute Birthdate. In
this situation, Birthdate is
called a stored attribute,
which is physically saved
to the database.
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Employee
Name
Address Birthdate Salary
Age

9. References
1. https://resources.saylor.org/wwwresources/archived/site/wp-
content/uploads/2014/12/CS403-1.10-Database-Design-2nd-Edition-CCBY.pdf
2. Database System Concepts 6th edition by korth and Sudarshan
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