Tài liệu Activity 5.1: Identifying Keys in the Logical Model pdf

Activity 5.1: Identifying Keys in the
Logical Model
In this activity, you will identify primary, foreign, and (if necessary) composite
keys in the logical data model for Ferguson and Bardell, Inc.
Objectives
After completing this activity, you will be able to:
!
Identify primary, foreign, and composite keys in a logical data model.
!
Select a primary and foreign key type that is appropriate for a given entity.

Before You Begin
This activity will be completed individually, with a class discussion to follow.
Time to complete this activity: 20 minutes

22 Activity 5.1: Identifying Keys in the Logical Model



Exercise 1:
Identifying Keys
In this exercise, you will identify primary, foreign, and composite keys for a
logical data model based on the Ferguson and Bardell, Inc. case study.
!
Specify the keys in a logical data model
1. Review the ER diagram on the next page.
2. Identify the areas of the ER diagram for which keys are necessary.
3. Write the keys in the space provided on the ER diagram.
4. Label each key as necessary, using the following syntax:
Primary Key: (PK)

Foreign Key: (FK)
Composite Key: (CK) Draw a line under the attributes used to define the
composite key, and then label their types as Primary or Foreign.

Next, you will discuss your answers with the class.
Activity 5.1: Identifying Keys in the Logical Model 23




Name
Address
SSN
E-Mail
Type
Salary
BillableRate
Employee
EmployeeFirstName
EmployeeLastName
ClientName
ClientLocation
Date
Expenses
TotalHours
BillableHours
Description
Timesheet
ClientName
ClientAddress

ClientCity
ClientState
ClientZip
Date
Amount
Work Description
Invoice
Name
Address
City
State
Zip
Client
Make
Model
VIN
Year
BeginMileage
EndMileage
MaintenanceCost1
MaintenanceDesc1
MaintenanceDate1
MaintenanceMiles1
MaintenanceCost2
MaintenanceDesc2
MaintenanceDate2
MaintenanceMiles2
MaintenanceCost3
MaintenanceDesc3
MaintenanceDate3

MaintenanceMiles3
Vehicle
Is Issued
Completes
Is Made From
Is Sent To
Contracts With
JobDesc
TaskDesc
Job
Bills Time To
Client
Employee
StartDate
EndDate
Description
Contract
Purchases
1
1..
∞
∞∞
∞
1
0..
∞
∞∞
∞
1
1..

∞
∞∞
∞
0..
∞
∞∞
∞
1
1
1..
∞
∞∞
∞
1
1..
∞
∞∞
∞
0..
∞
∞∞
∞
0..
∞
∞∞
∞

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