Database Reference
In-Depth Information
Customer
CustomerNum CustomerName
Balance CreditLimit RepNum LastName FirstName
148
Al's Appliance
$6,550.00
$7,500.00
20
Kaiser
Valerie
and Sport
282
Brookings Direct
$431.50
$10,000.00
35
Hull
Richard
356
Ferguson's
$5,785.00
$7,500.00
65
Perez
Juan
168
408
The Everything
$5,285.25
$5,000.00
35
Hull
Richard
Shop
462
Bargains Galore
$3,412.00
$10,000.00
65
Perez
Juan
524
Kline's
$12,762.00
$15,000.00
20
Kaiser
Valerie
608
Johnson's
$2,106.00
$10,000.00
65
Perez
Juan
Department
Store
687
Lee's Sport
$2,851.00
$5,000.00
35
Hull
Richard
and Appliance
725
Deerield's
$248.00
$7,500.00
35
Hull
Richard
Four Seasons
842
All Season
$8,221.00
$7,500.00
20
Kaiser
Valerie
Customer
Rep
RepNum LastName FirstName
20
CustomerNum CustomerName
Balance CreditLimit RepNum
Kaiser
Valerie
148
Al's Appliance
$6,550.00
$7,500.00
20
and Sport
35
Hull
Richard
282
Brookings Direct
$431.50
$10,000.00
35
65
Perez
Juan
356
Ferguson's
$5,785.00
$7,500.00
65
408
The Everything
$5,285.25
$5,000.00
35
Shop
462
Bargains Galore
$3,412.00
$10,000.00
65
524
Kline's
$12,762.00
$15,000.00
20
608
Johnson's
$2,106.00
$10,000.00
65
Department Store
687
Lee's Sport
$2,851.00
$5,000.00
35
and Appliance
725
Deerield's Four
$248.00
$7,500.00
35
Seasons
842
All Season
$8,221.00
$7,500.00
20
FIGURE 5-12
Conversion to third normal form
Have you now corrected all previously identified problems? A sales rep
'
s name appears only once,
thus avoiding redundancy and simplifying the process of changing a sales rep
s name. With this design, it is
not possible for the same sales rep to have different names in the database. To add a new sales rep to the
database, you can add a row in the Rep table without requiring the rep to have at least one assigned cus-
tomer. Finally, deleting all the customers of a given sales rep will not remove the sales rep
'
'
s record from the
Rep table, retaining the sales rep
s name. In addition, you can reconstruct all the data in the original table
from the data in the new collection of tables. All previously mentioned problems have indeed been solved.
'
