this is about our presentation about ERD

1. GROUP MEMBERS NO. MATRIX GROUP
ELIS ERVINA BINTI SULIMAN 2012967249 CS 241 3B
ERLIA NADIA BINTI AB. MALEK 2012996329 CS 241 3B
NORA SYAMIMI BINTI KHAIRUDDIN 2012949807 CS 241 3B
NORHIDAYAH BINTI ZULKEFLI 2012755781 CS224 3A

3. CAR
MOD_CODE
CAR_VIN CAR_COLOR
CAR_YEAR
CHEN MODEL
CAR
PK CAR_VIN
MOD_CODE
CAR_YEAR
CAR_COLOR
CROW’S FOOT MODEL

4. BASIC SYMBOLS

5. TERMINOLOGY
Entity type
a collections of things, represent collection of physical things such as
person, places, event, or things.
Attributes
A property of an entity type or relationship. Each attributes has a data
type that defines the kind of values and permission operation on the
attributes.
Relationship
association among entity types, usually two-way or bidirectional. In
crow’s foot notation relationship names appear on the line connecting
the entity types involved in the relationship.

6. Connectivity
To describe the relationship classification
Cardinality
A constraint on the number of entities that participate in a
relationship. Has minimum and maximum cardinality for both
directions of a relationship.
EXAMPLE

7. MANY-TO-
MANY (M-N)
ONE-TO-
MANY
(1-M)
ONE-TO-
ONE (1-1)

9. Classification of cardinalities
 Minimum cardinality based:
 A min cardinality of 1>= (one or more) indicates a
mandatory relationship which creates an existence
dependent
 A min cardinality of 0 indicates an optional relationship
 Maximum cardinality based
 A max cardinality of 1 means the relationship is single-
valued or functional (in math, value 1)
 1-1 (less common), 1-M (common), M-N
(common).

10. Summary of Cardinalities

12. Type of entity
Type of
attribute
Relationship
strength
Degree of
relationship

13. • The entity is
existence
independent
Strong
entity
• The entity is
existence
dependent
Weak
entity

14. Strong relationship
• Identifying
relationship
• Exist when PK of
related entity
contains PK
component of
parent entity
Weak relationship
• Non-identifying
relationship
• Exist if PK of
related entity does
not contain PK
component of
parent entity

15. Example
Weak relationship but strong
entity
strong relationship but weak
entity

16. Attribute Composite
attribute
Simple
attribute
Single
value
attribute
Multivalu
ed
attribute
Derived
attribute
Definition Attribute that
can be further
subdivided to
yield
additional
attribute
Attribute
that cannot
be
subdivided
Attribute
that can
have only a
single value
Attribute
that can
have many
value
Attribute
whose value is
calculated from
other attribute
Example Address
( street, city,
zip code, state)
age, sex,
marital
status
social
security
number, ic
number
level of
education,
car’s color
An emp_age,
May be found
by compUting
the integer
value of the
different
between the
current date
and the
emp_dob

17. Degree of Relationships
 Unary
Exist when an association is maintained within a single
entity.
Binary
Exist when two entities are associates in a relationship.
 Ternary and higher-degree relationship
Three entities are associates and higher-order
relationship does allow the designer some latitude
regarding the semantic of a problem.

18. SPECIALIZATION/GANERALIZATION
 Concepts of specialization/generalization is associated
with special types of entities known as
SUPERCLASSES
SUBCLASSES
And the process of
 ATTRIBUTE INHERITANCE

19. SUPERCLASS
• Entity type that have
one or more distinct
subgrouping of it
occurrences, which
must be represented
in a data model
SUBCLASS
• A distinct
subgrouping
occurrences of an
entity type, which
must be represented
in a data model.

20. SUPERCLASS/SUBCLASS RELATIONSHIP
 Each member of a subclass is also a member of the
superclass. In other word the entity in subclass is the
same entity in superclass, but have distinct role.
 It has one to one relationship( superclass/ subclass
relationship)
 E.g: Staff/Manager has superclass/subclass
relationship.

21. EXAMPLES
STAFF
MANAGER
SALES
PERSONNEL
SECRETARY
SUPERCLASS
SUBCLASS

22. ATTRIBUTE INHERITANCE
 An entity in a subclass represent the same ‘real world’
object in the superclass.
 E.g: A member of the SALES PERSONAL inherit all the
attribute of the STAFF superclass such as
(staffno, name, position, salary) and together with
those sales PERSONAL SUBCLASS
(sales area,car allowance)

23. GENERALIZATION/SPECIALIZATION
 To make the generalization/specialization we should
identify first their distinguish characteristics and
common characteristics for the attribute that we want
to make generalization.
 Hence, when we know both of them we can separate
the attribute that have common characteristic in
superclass while their different characteristic in every
subclass.

24. GANERALIZATION SPECIALIZATION
•The process of minimizing the
differences between entities by
identifying their common
characteristic.
•The process of maximizing the
difference between members of entity
by identifying their distinguishing
characteristic.
•The bottom-up process of identifying a
higher level, more generic entity
superclass from lower level entity
subclass.
•The top-down process of identifying
lower level, more specific entity subtype
from a higher level entity super type.

25. CONSTRAINT ON SPECIALIZATION
OR GANERALIZATION
DISJOINTNESS CONSTRAINT COMPLETENESS CONSTRAINT
•DEF: means that the subtypes
in a generalization hierarchy do
not have any entities in
common
•DEF: means that every entity of super
type must be an entity in one of the
subtypes
•It can be symbolized by : D •It can be symbolized by: C

26. Staff
StaffNo(PK)
Name
Position
Salary
Branch
BranchNo(PK)
Address
Street
City
postcode
HAS
1,1 1,M
Lets assume that we have this entity type. For the
position attribute (STAFF)it will have manager,
clerk ,cleaner, sales personnel and etc. Hence for
maximizing the difference between members of
entity ,we identifying their distinguishing
characteristic. The process called as
generalization.
GANERALIZATION

27. Staff
StaffNo(PK)
Name
Position
Salary
Branch
BranchNo(PK)
Address
Street
City
postcode
HAS
1,1 1,M
Manager
mgStartDate
bonus
SalesPersonnel
salesArea
carAllowance
Secretary
typingSpeed
{D,C}
Distinguishing characteristic
GANERALIZATION

28. Manager
Staff_no
Salary
mgStartDate
Bonus
SalesPersonnel
Staff_no
Salary
salesArea
carAllowance
Branch
BranchNo(PK)
Address
Street
City
postcode
1,1
1,1
manages
Product
Prod_no(PK)
Expired_dte
Prod_name
1,M
1,1
sales by
Lets assume that we have
this entity type. For the
manager and sales
personnel ,we can see
that they have the same
characteristics(attribute).
Hence we can
minimizing the
differences by creating
the other entity. The
process called as
specialization.
SPECIALIZATION
COMMON CHARACTERISTICS

29. Manager
Staff_no
Salary
mgStartDate
Bonus
SalesPersonnel
Staff_no
Salary
salesArea
carAllowance
Staff
StaffNo(PK)
Name
Position
Salary
{D,C}
Branch
BranchNo(PK)
Address
Street
City
postcode
Product
Prod_no(PK)
Expired_dte
Prod_name
manages
sales by
SPECIALIZATION

30. Branch
BranchNo(PK)
Address
Street
City
postcode
Staff
StaffNo(PK)
Name
Position
Salary
has
1..1 1..*
PartTimeTemporary
hourlyRate
FullTimePermanent
salaryScale
holidayAllowance
Secretary
typingSpeed
SalesPersonnel
salesArea
carAllowance
Manager
mgStartDate
bonus
1..1
1..1
manages { C} {D, C}
disjointness
constraint
Indicate
specialization/
generalization
Job role subclasses Contract employment
subclasses
EXAMPLE

31. Business Rule

32. Step for representation
 Find the entity
 Primary key
 Name the relationship of the connection among
business entity
 Know the connection between two entity
(1-m, 1-1, m-n)
 Find the cardinalities- restrict number of related
entities in a business situation
 Generalization hierarchies- classification of business
entities and organizational policies.