Microsoft Office Tutorials and References
In Depth Information
Session 1.1
Databases and Relationships
A collection of related tables is called a database , or a relational database . NSJI’s Seasonal
database contains two related tables: the Employer and NAICS tables, which Elsa created.
(The NAICS table contains North American Industry Classification System codes, which are
used to classify businesses according to their activities.) In Tutorial 2, you will create a
Position table to store information about the available positions at NSJI’s employer clients.
Sometimes you might want information about employers and their available positions.
To obtain this information, you must have a way to connect records in the Employer table
to records in the Position table. You connect the records in the separate tables through a
common field that appears in both tables.
In the sample database shown in Figure 1-2, each record in the Employer table has a
field named EmployerID, which is also a field in the Position table. For example, BaySide
Inn & Country Club is the third employer in the Employer table and has an EmployerID
field value of 10126. This same EmployerID field value, 10126, appears in three records
in the Position table. Therefore, BaySide Inn & Country Club is the employer with these
three positions available.
Databases
Database relationship between tables for employers and positions
Figure 1-2
Employer table
PhoneNumber
EmployerID
EmployerName
EmployerAddress
10122
BeanTown Tours
105 State Street, Boston, MA 02109
617-451-1970
10125
75 Atlantic Avenue, Boston, MA 02110
Boston Harbor Excursions
617-235-1800
10126
BaySide Inn & Country Club
354 Oceanside Drive, Brewster, MA 02631
508-283-5775
10190
The Briar Rose Inn
105 Queen Street, Charlottetown PE C1A 8R4
902-626-1595
primary
keys
10191
Windsor Alpine Tours
14 Longmeadow Road, Laconia, NH 03246
603-266-9233
10198
Trudel Spa & Resort
40 Rue Rivard, North Hatley QC J0B 2C0
819-842-7783
common field
three positions
for BaySide Inn &
Country Club
foreign key
Position table
PositionID
PositionTitle
EmployerID
Hours/Week
32
24
24
32
24
30
35
40
32
2040
2045
2053
2066
2073
2078
2079
2082
2111
Waiter/Waitress
Tour Guide
Host/Hostess
Lifeguard
Pro Shop Clerk
Ski Patrol
Day Care
Reservationist
Kitchen Help
10126
10122
10190
10198
10126
10191
10191
10125
10126
Each EmployerID value in the Employer table must be unique, so that you can distin-
guish one employer from another and identify the employer’s specific positions available
in the Position table. The EmployerID field is referred to as the primary key of the
Employer table. A primary key is a field, or a collection of fields, whose values uniquely
identify each record in a table. In the Position table, PositionID is the primary key.
 
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