Tài liệu Activity 5.2: Normalizing Data doc

Activity 5.2: Normalizing Data
In this activity, you will normalize a set of entities from the Ferguson and
Bardell, Inc. case study.
Objectives
After completing this activity, you will be able to:
• Normalize a logical data design to third normal form.

Before You Begin
This activity is completed individually, with a class discussion to follow.

Time to complete this activity: 30 minutes

26 Activity 5.2: Normalizing Data




Exercise 1:
Creating a Normalized Data Design
In this exercise, you will evaluate a logical design and then redesign it based on
your knowledge of keys and normalization to produce a fully normalized data
design.
!
Normalize the design to third normal form
1. Review the ER diagram on the next page.
2. Identify the areas of the ER diagram in which normalization rules are
violated as follows:
a. Data is duplicated within multiple entities.
b. Attributes of an entity are not directly associated with that entity.
c. Each entity does not have attributes that uniquely define each instance.

3. On the page opposite the ER diagram, sketch out your own ER diagram
with normalization applied to the third normal form.

Keep in mind that the data design shown on the next page is not optimized
in any way. The keys provided may need to be redesigned as part of the
normalization process.


Next, you will discuss your answers with the class.

Tip
Activity 5.2: Normalizing Data 27



Name
Address
SSN
E-Mail
Type
Salary
BillableRate
EmployeeID(PK)
Employee
ClientID(FK)
EmployeeID(FK)
JobID(FK)
EmployeeFirstName
EmployeeLastName
ClientName

ClientLocation
Date
Expenses
TotalHours
BillableHours
Description
TimesheetID(PK)
Timesheet
ClientID(FK)
TimesheetID(FK)
ClientName
ClientAddress
ClientCity
ClientState
ClientZip
Date
Amount
Work Description
InvoiceID(PK)
Invoice
Name
Address
City
State
Zip
ClientID(PK)
Client
EmployeeID (FK)
Make
Model

VIN
Year
BeginMileage
EndMileage
MaintenanceCost1
MaintenanceDesc1
MaintenanceDate1
MaintenanceMiles1
MaintenanceCost2
MaintenanceDesc2
MaintenanceDate2
MaintenanceMiles2
MaintenanceCost3
MaintenanceDesc3
MaintenanceDate3
MaintenanceMiles3
VehicleID(PK)
Vehicle
Is Issued
Completes
Is Sent To
Contracts With
JobDesc
TaskDesc
JobID(PK)
Job
Bills Time To
ClientID(FK)
EmployeeID(FK)
StartDate

EndDate
Description
ContractID(PK)
Contract
Purchases
1
1
∞
∞∞
∞
1
0
∞
∞∞
∞
1
1
∞
∞∞
∞
0
∞
∞∞
∞
1
1
1
∞
∞∞
∞

1
1
∞
∞∞
∞
Is Made From
0
∞
∞∞
∞
0
∞
∞∞
∞




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