Lesson 16
AOIT Database Design
Lesson 6 Creating a Conceptual Model
AOIT Database Design
Lesson 6
Creating a Conceptual Model
Teacher Resources
Resource
Description
Teacher Resource 6.1
Answer Key: User Requirements Analysis
Teacher Resource 6.2
Presentation and Notes: Determining User Requirements (includes
separate PowerPoint file)
Teacher Resource 6.3
Assessment Criteria: Statement of Requirements Writing
Assignment
Teacher Resource 6.4
Guide: Creating a Conceptual Model
Teacher Resource 6.5
Assessment Criteria: Culminating Project Conceptual Model
Teacher Resource 6.6
Key Vocabulary: Creating a Conceptual Model
Teacher Resource 6.7
Bibliography: Creating a Conceptual Model
Teacher Resource 6.1
Answer Key: User Requirements Analysis
Note: The following represent possible student responses;
answers may vary.
User Type (Role, Function, and Needs)
Information Needs for This User Type
User type: Executive
Role: Overall responsibility for the organization
Function: Oversee budget and membership
Needs: Printed reports
This type of user needs reports that provide the following
information:
· Monthly sales totals
· Breakdown of customers by state and area code
· Most popular merchandise items
· Detailed order data of top customers
User type: Office Manager
Role: Manage catalog sales operation
Function: Order fulfillment, record keeping, data entry, contact
information
Needs: Wide range of order and product information
This type of user needs …
Complete information for each order and product
User type: Program Manager
Role: Day-to-day responsibility for ADA activities
Function: Responsible for the dolphin store’s success
Needs: Information about merchandise
This type of user needs …
Which suppliers provide which products
How products are selling
Inventory information
User type: Administrative Assistant
Role: Help others as needed
Function: Run the dolphin store
Needs: How to enter data and run reports
This type of user needs …
Same information as others (except for the Executive)
Instructions for entering data
Instructions for running reports needed by others
Teacher Resource 6.2
Presentation Notes: Determining User Requirements
Before you show this presentation, use the text accompanying
each slide to develop presentation notes. Writing the notes
yourself enables you to approach the subject matter in a way that
is comfortable to you and engaging for your students. Make this
presentation as interactive as possible by stopping frequently to
ask questions and encourage class discussion.
This presentation explains how database designers determine user
requirements.
Presentation notes
Determining user requirements requires careful, detailed
analysis. Database designers have found that the best way to make a
thorough analysis is to categorize users according to their roles
and then to look at the functions that people in each role perform.
Finally, they look at the information users need to perform each
function. In the next slides, you will get a clearer idea of how to
determine roles, functions, and information needs.
Presentation notes
Just like a play has actors who each play a different role,
different people play different roles in businesses and
organizations. Often, people who play different roles also require
different kinds of information. A role is like a name or a job
title that defines what the person’s place is in an organization or
business.
Presentation notes
People in almost every role have multiple functions. In order to
determine the information needs of a user, you need to think
through the different functions they perform, and then you can list
the information they need to perform each function.
For example, a person whose role is “Pizza Delivery Person” has
at least two functions:
Deliver the pizza
Collect payment for the pizza
This person needs address information to deliver the pizza.
He or she also needs pricing information to collect payment for
the pizza.
Presentation notes
Database designers cannot figure out the needs on their own;
they must work with the users who are familiar with how they do
their work and the information they need to do it. For example, the
database designer might be able to guess that a teacher needs a
list of students. But the teacher might need to tell the designer
that she also needs parent contact information for each student.
Creating a list of user needs is a collaborative effort.
Developing your culminating project database may require
additional contact with your client via email. You are very likely
to have additional questions that were not answered during the
client interview.
Presentation notes
Information needs must be translated into user requirements.
These user requirements form the basis for the information that
will be included in a database. It’s important to come up with an
exhaustive list of user requirements.
If you are creating a database for an entirely new organization,
there may not be an existing database. Otherwise, there is some
kind of existing database to run the organization. The existing
database might not be an electronic database. It could be stacks of
invoices, purchase vouchers, and handwritten order forms. But it
will help you determine what the user requirements are and what
data must be included in the database.
User requirements might also include more than just information
requirements. There might be specific requirements about certain
views or printouts or uses of information (for example, the ability
to prepare an order and print it out to send to a vendor, or the
ability to search for a vendor in the database by name or type).
These could influence the organization of the database and what
additional attributes might be needed. Think about any reports and
queries that are defined in the project definition document as part
of the deliverable.
Presentation notes
This scenario of the Tae Kwon Do Academy will take you through
the process of determining user requirements. Start by defining the
roles from the information on this slide.
Presentation notes
Listing the functions for each role helps ensure that you
explore all of the types of information different groups of users
might need. For example, if you forget that the office staff
purchases supplies, you might forget to put supplier information in
the database.
Presentation notes
Not all of the users’ needs may be included in a single
database.
Some information that users need may be stored in a separate
database. For example, the office manager is responsible for paying
teacher salaries. Salary information for employees is separate from
student information and may require a different database.
Presentation notes
When you start writing the user requirements, you may find that
users with different roles need some of the same data. Be as
specific as you can in identifying what each type of user needs.
For example, one user may just require student names, whereas
another user requires student names, addresses, and phone
numbers.
Note that requirements can be very specific and that they
include requirements for “functionality” such as predefined reports
and queries.
Presentation notes
All users can help you learn the business rules and
constraints.
People at the top of the organization are responsible for many
of the business rules organizations have. But all the employees
will have some knowledge of them. Data-entry clerks who do the
detail work may actually have the best idea of what data can be
entered and what business rules they must follow.
Presentation notes
This procedure helps ensure that a database is on target from
the start. By taking the time to carefully define the user
requirements, you can greatly reduce the amount of reworking you
will need to do after the actual database is developed.
Presentation notes
Teacher Resource 6.3
Assessment Criteria: Statement of Requirements Writing
Assignment
Student
Names:______________________________________________________________
Date:_______________________________________________________________________
Using the following criteria, assess whether the students met
each one.
Met
Partially Met
Didn’t Meet
The statement of requirements clearly identifies what the
customer should expect to be included in the finished product.
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The statement of requirements covers all aspects of what the
client deems to be important.
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The statement of requirements shows an understanding of how the
client perceives that the database will be used.
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The statement of requirements identifies any limitations imposed
by business rules.
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The Microsoft Word document looks professional because it is
laid out with clear paragraphs or uses bulleted lists so that the
reader can easily identify requirements. It has no spelling or
grammatical errors.
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Additional Comments:
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Teacher Resource 6.4
Guide: Creating a Conceptual Model
Use the information in this guide as a basis for the guided
practice activity that teaches students how to create a conceptual
model.
The Big Picture
A conceptual model provides a high-level picture of what the
data will look like. This is where you decide what should be
included in the database and take a first stab at organizing it. A
conceptual model generally includes the following:
The entities to be included in the database (an entity is a
person, place, thing, event, or concept about which data is
collected)
The attributes of each entity
The business rules that put constraints on the entities
The relationships between entities
Entities and Attributes
Begin your discussion by talking about the difference between
entities that should be tracked in the database and the attributes
of those entities. An entity should identify a person, place,
thing, event, or concept that you need to track in your database in
order to meet a user requirement. The attributes are the
characteristics of these entities that are relevant to the user
requirements.
So, the first step is to go through the list and ask, “Does this
entity identify a person, place, thing, event, or concept that I
need to track to meet a user requirement?” Work with students to
cross out any entities that are irrelevant.
The next step is to figure out whether some of the entities look
more like attributes than entities. Although you may not be able to
tell for certain at this stage which items are entities and which
are attributes, in the conceptual model you need to take a first
stab at organizing them into entities and attributes. For example,
the list of entities the class created might include the
following:
Customer
Customer Name
Customer Phone Number
Product
Price
Order Number
Invoice
Since Customer Name and Customer Phone Number give you
information about the customer, they are likely candidates to be
attributes of the entity Customer. Since Price gives you
information about the product, it will be an attribute of the
entity Product. Since the order number might be used to identify
the invoice, Order Number could be an attribute of the entity
Invoice. (Note that the entity Invoice may later need to be broken
down into several entities; for right now, just work on getting a
general structure.)
Work with the class to develop a table such as the following,
adding attributes to entities as necessary. This table gives a
fairly good start for a conceptual model of the dolphin
database.
Entity
Attributes
Product
Product Name, Product Description, Price
Customer
Customer Name, Customer Phone Number
Order
Order Number, Date Shipped
Supplier
Supplier Name, Supplier Address
Shipper
Shipper Address, Shipping Cost
Business Rules
The conceptual model identifies the business rules that go with
each entity. So, for example, if you add the following business
rules for the dolphin database, the Customer and Product entities
would look something like what is shown below these business
rules:
Customers live in the United States and Canada only.
All merchandise prices must be $3 or more.
No more than 15 units can be in stock of any one product.
Customer
Product
Business rules:
Attributes
Business rules:
Attributes
Only US and Canada addresses and phone numbers
Customer Name
- All merchandise prices must be $3 or more
- No more than 15 units can be in stock of any one product
Product Description
Phone Number
Price
Address
Number in Stock
Relationships
Since relationships are essential to database design, a
conceptual model needs to give some ideas about which entities are
related to each other. For example, students should be able to
predict that customers are related to products, but customers are
probably not related to suppliers or shippers. Work with students
to come up with a simple diagram such as the following that shows
relationships.
Teacher Resource 6.5
Assessment Criteria: Culminating Project Conceptual Model
Student
Names:______________________________________________________________
Date:_______________________________________________________________________
Using the following criteria, assess whether the students met
each one.
Met
Partially Met
Didn’t Meet
The model shows a clear understanding of what entities and
attributes are.
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Entities correspond to the client’s most important user
requirements.
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The attributes listed for each entity correspond to the
information that the user needs.
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Business rules are included with the entities affected by
them.
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The model clearly shows which entities are related.
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The model is neat, legible, and professional.
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Additional Comments:
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Teacher Resource 6.6
Key Vocabulary: Creating a Conceptual Model
Term
Definition
attribute
A characteristic of an entity.
business rule
A policy or procedure that restricts how an organization
operates and that must be reflected in the database.
conceptual model
A technology-independent concept of what the data looks
like.
entity
A person, place, thing, event, or concept about which data is
collected.
relationship
An association between two entities.
statement of requirements
A detailed description of the database to be delivered to the
client, including its display, how data is updated, how users
navigate it, and how quickly data can be retrieved from it.
Teacher Resource 6.7
Bibliography: Creating a Conceptual Model
The following sources were used in the preparation of this
lesson and may be useful for your reference or as classroom
resources.
Print
Oppel, Andy. Databases Demystified: A Self-Teaching Guide.
Emeryville, CA: McGraw-Hill/Osborne, 2004.
Taylor, Allen G. Database Development for Dummies. Hoboken, NJ:
Wiley, 2001.
Copyright © 2009–2014 NAF. All rights reserved.
Copyright © 2009–2014 NAF. All rights reserved.
