This paper above describes a brief touch on conceptual data modelling, and creating rich E-R Diagrams.

1. GROUP ASSIGNMENT
OF SYSTEM ANALYSIS
AND DESIGN
GROUP MEMBERS
RINGUYENEZA Salton
(221004471)
UMULISA Devine (221003028)
NDAYISABA Christopher
(221009718)

2. STRUCTURING
SYSTEM
REQUIREMENTS
TOPIC:
conceptual data
modeling

3. CONCEPTUAL DATA MODELING
• The Process of Conceptual Data Modeling
• Deliverables and outcomes
• Gathering Information for Conceptual Data Modeling
• Entity-Relationship Modeling
• Conceptual Data Modeling and the E-R Model
• Selecting the best alternative design strategy.
• The Process of Selecting the Best Alternative Design Strategy
Content:
3

4. 4
What Is the Data Modeling?
Before talking about conceptual data model, we first need to know data model and the use of
data model.
data modeling is the process of describing real-world data – its relationships, features, and
attributes – in a structured document like an ER (entity-relationship) diagram.
The data model acts as a Master plan that the data analyst will use to convert all the data
involved in business processes into a database.
In data modeling, we go through three different stages:
Conceptual data model: The most abstract data model that describes the data elements
without much detail.
Logical data model: A conceptual model with more technical details.
Physical data model: A logical model with all the details of the physical database

5. WHAT IS THE CONCEPTUAL DATA
MODELING?
Conceptual data models contain only:
The real-world entities that are our main data elements.
Their relationships.

6. HOTEL RESERVATION SYSTEM
6
This is an ER diagram for a hotel reservation
system. In this business scenario, hotels can
be registered in the system and customers
can reserve rooms in their preferred hotels.
Each hotel has many rooms. A customer can
make many reservations, and one reservation
should belong to one customer. During their
stay, a customer can get many services, which
will be added to that reservation. When the
customer checks out, the final bill is prepared
based on their reservation records.

7. 7
This conceptual data model has six entities (Hotel, Room, Reservation, Customer, Service, and Bill)
and five relationships, as shown below:
Hotel Room: A one-mandatory-to-many-mandatory relationship.
Room Reservation: Each room can be in many reservations, including one active reservation and
many past reservations. Each reservation can have one or many rooms.
Therefore we have a many-mandatory-to-many-optional relationship between the Room and
Reservation This can be simplified by creating an association between these entities.
Reservation Service: A one-mandatory-to-many-optional relationship.
Customer Reservation: A one-mandatory-to-many-optional relationship.
Customer Bill: A one-mandatory-to-many-optional relationship.

8. THE PROCESS OF CONCEPTUAL DATA
MODELING
If a system exists, you begin conceptual data modeling by developing a data model for a
system being replaced.
Deliverables and outcomes
Most organizations today do conceptual data modeling using entity-relationship
modeling, which uses a special notation of rectangles, diamonds, and lines to represent
as much meaning about data as possible.
Thus the primary deliverable and Outcome from the conceptual data modeling is an
entity relationship diagram.
Gathering Information for Conceptual Data Modeling
You typically do data modeling from a combination of perspectives:
Top down approach
Bottom up approach

9. INTRODUCTION TO ENTITY-
RELATIONSHIP MODELING
9
The basic E-R modeling notation uses three main constructs:
data entities, relationships, and their associated attributes.
Entity-relationship diagram (or E-R diagram) is a detailed,
logical, and graphical representation of the data for an
organization.
ENTITIES:
Entity : is a person, place, object, event, or concept in the user environment
about which the organization wishes to maintain data.
Have 2 different type which is:
Entity type: is a collection of entities that share common properties or characteristics.
Entity instance: is a single occurrence of an entity type.

10. 10
 Attributes : An attribute is a property or characteristic of an entity that is of interest to the organization.
STUDENT: Student ID, Student Name, Address, Phone Number, Major
AUTOMOBILE: Vehicle ID, Color, Weight, Horsepower
EMPLOYEE: Employee ID, Employee Name, Address, Skill
Candidate keys and identifiers:
Candidate keys is an attribute (or combination of attributes) that uniquely identifies each instance of an
entity type.
An identifier is a candidate key that has been selected to be used as the unique characteristic for an
entity type.
multivalued attribute may take on more than one value for each entity instance.
Suppose that, Skill is one of the attributes of EMPLOYEE. If each employee can have more than one
Skill, then it is a multivalued attribute.
Conceptual Data Modeling and the E-R Model:
The goal of conceptual data modeling is to capture as much of the meaning of data as possible

11. RELATIONSHIP AND CARDINALITY
11
Relationship is an association between the instances of one or more entity types that are of interest to
the organization.
An association usually means that an event has occurred or that some natural linkage exists between entity
instances.
Degree (Types) of a Relationship
The degree of a relationship, is the number of entity types that participate in that relationship.
The three most common relationships in E-R diagrams are unary (degree one), binary (degree two), and
ternary (degree three).
Unary Relationship Also called a recursive relationship, a unary relationship is a relationship between the
instances of one entity type.
A binary relationship is a relationship between instances of two entity types and is the most common type of
relationship encountered in data modeling.
A ternary relationship is a simultaneous relationship among instances of three entity types.
We also know other most known types of relationship in Database are:
 ONE TO ONE relationship
 ONE TO MANY relationship
 MANY TO MANY relationship

12. CARDINALITY
12
Cardinalities in Relationships
Suppose that two entity types, A and B, are connected by a relationship.
The cardinality of a relationship is the number of instances of entity B that can be associated
with each instance of entity A.
Minimum and Maximum Cardinalities
The minimum cardinality of a relationship is the minimum number of instances of entity B
that may be associated with each instance of entity A.
While
The maximum cardinality is the maximum number of instances.
Associative Entities : attributes may be associated with a many-to-many
relationship as well as with an entity.

13. SELECTING THE BEST ALTERNATIVE DESIGN
STRATEGY.
13
Design strategy is a particular approach to developing an information system.
It includes statements on system’s functionality, hardware and system software platform.

14. THE PROCESS OF SELECTING THE BEST
ALTERNATIVE DESIGN STRATEGY
14
Dividing requirements into different sets of capabilities, ranging from the bare
minimum that users would accept (the required features) to the most elaborate
and advanced system the company could afford to develop (which includes all
the features desired by all users).
Enumerating different potential implementation environments (hardware,
system software, and network platforms) that could be used to deliver the
different sets of capabilities.
Proposing different ways to source or acquire the various sets of capabilities for
the different implementation environments.