Lab 09 – Normalization — For ron tarr
(UNF, 1NF)
Objective:
· Students create the Un-normalized Form (UNF) relation from a user view.
· Students identify a Multi-valued Dependency (a.k.a. Repeating Group )
· Students create the First Normal Form (1NF) relation from the UNF.
Submission:
Only submit the last section, which has just a 2 line result. However it is extremely important that you work through the first part.
This submission is simpler because receiving 40 emails, opening them and posting the marks takes a lot of time.
When you get to the last page you are going to copy the 2 or 3 lines into the body of the email and mail it to me.
Make sure you email has Lab09 and your name and section
in the subject line
Definitions:
Definition: Normalization is the process of assigning attributes to relations in such a way that data redundancies are reduced or eliminated.
Definition: User Views can be individual descriptions, reports, forms, or lists of data that are required to support the operations of a particular database user.
Definition: Unnormalized form (UNF) is a relation that contains one or more Multi-valued Dependencies.
Definition: A Multi-valued Dependency is an attribute or collection of attributes within a relation that has multiple values for a single value of the primary key for that relation.
Definition: A relation is in 1NF if it does not contain any multi-valued dependencies.
Instructions:
Step 1: Create UNF Relation from a User View. The goal here is to create a single relation for the data found in the user view. The method used is:
· Examine the user view
· Identify all attributes
· Describe the user view using DBDL
Here is an example of a user view. This reports lists the customers of the Premiere Corporation.
Premiere Corporation Customer List
CustNo
Name
Street
City
State
ZipCode
SalesRepNo
124
Sally Adams
482 Oak
Lansing
MI
49224
03
256
Ann Samuels
215 Pete
Grant
MI
49219
06
311
Don Charles
48 College
Ira
MI
49034
12
315
Tom Daniels
914 Cherry
Kent
MI
48391
06
405
Al Williams
519 Watson
Grant
MI
49219
12
412
Sally Adams
16 Elm
Lansin
MI
49224
03
522
Mary Nelson
108 Pine
Ada
MI
49441
12
A. Examine the user view: As you examine this report, you can see that it contains a title, a line of column headings and the body of the report. Each line in the body of the report contains data about a particular customer. For example we can see that in the first line of the body of the report, there is data about Customer 124. This customer’s name is Sally Adams and she lives at 482 Oak in Lansing, Michigan (MI). The Sales Representative who calls on Sally Adams is Sales Rep Number 03.
B. Identify all attributes: The attributes (or characteristics) of a User View can often be found by simply looking at the column headings. In our Customer Report we see that we have the following attributes: Customer Number, Customer Name, Street, City, State, Zip Code and Sales Representative Number.
C. Describe the relation using DBDL: Database Design Language (DBDL) is a standardized way of describing relations of a relational database. You describe a relation by:
a. Choose an appropriate name for the relation. We chose to name our relation CUSTOMER because each line in the report describes customer data.
b. List the attributes you found in the user view inside square brackets, giving each attribute a suitable attribute name. Note: calculated fields or derived fields should not be included in the DBDL
c. Determine which attribute would be suitable as a primary key and underline that attribute.
The DBDL for the relation resulting from our Customer user view would look as follows:
CUSTOMER [ CustNo, CustName, CustStreet, CustCity, CustSt, CustZip, CustRep ]
Now you try it. Examine the following report:
Premiere Corporation Parts List
Part Number
Part Description
Qnty On Hand
Class
Warehouse
On Hand
Price
AX12
Iron
104
HW
3
24.95
AZ52
Dartboard
20
SG
2
12.95
BA74
Basketball
40
SG
1
29.95
BH22
Cornpopper
95
HW
3
24.95
BT04
GasGrill
11
AP
2
149.99
BZ66
Washer
52
AP
3
399.99
CA14
Griddle
78
HW
3
39.99
CB03
Bike
44
SG
1
299.99
CX11
Blender
112
HW
3
22.95
CZ81
Treadmill
68
SG
2
349.95
What type of data does each line in the report represent? _________________________________________________________________________
_________________________________________________________________________
What attributes can you identify from the user view?
________________________________ ________________________________
________________________________ ________________________________
________________________________ ________________________________
What would be a suitable name for the UNF relation? ___________________________
Which attribute would be suitable as a primary key? ___________________________
Describe the UNF relation using DBDL:
_____________________________________________________________________________
Step 2: Recognize Multi-valued Dependencies.
For example, looking at the following User View, we see that for each Customer number, it is possible to have multiple values for the order number and order date attributes. Therefore the order number and date are a multi-valued dependency.
Premiere Corporation Customer Orders
Customer Number
Name
Order Number
Order Date
124
Sally Adam
12489
2016-09-02
12500
2016-09-05
256
Ann Samuels
12495
2016-09-04
311
Don Charles
12491
2016-09-02
315
Tom Daniels
12494
2016-09-04
522
Mary Nelson
12498
2016-09-05
12504
2016-09-05
Identify multi-valued dependencies in DBDL by placing brackets around them. For example the DBDL for this User View would look like this:
CUSTOMER [ CustNo, CustName, (OrderNum, OrderDate) ]
Notice the brackets around the OrderNum and Orderdate attributes. This quickly and easily identifies a multi-valued dependency to someone who is reading the DBDL.
Common Mistake: A common mistake is to incorrectly identify repeating data as a multi-valued dependency. For example, the previous report could also have been printed in the following way:
Premiere Corporation Customer Orders
Customer Number
Name
Order Number
Order Date
124
Sally Adam
12489
2016-09-02
124
Sally Adam
12500
2016-09-05
256
Ann Samuels
12495
2016-09-04
311
Don Charles
12491
2016-09-02
315
Tom Daniels
12494
2016-09-04
522
Mary Nelson
12498
2016-09-05
522
Mary Nelson
12504
2016-09-05
The fact that the Customer Number and Name for Sally Adams and Mary Nelson have been repeated on multiple lines does not make Customer Number and Name a multi-valued dependency! You should still identify that for one customer number, there are multiple values for the order number and date. Note that this does not mean that EVERY customer number will have multiple order numbers, just that this user view shows that it is possible for some customer numbers to have multiple values for Order Number and Date. The Multi-valued Dependency must be identified in the DBDL. Note also that it is possible to have more than 1 multi-valued dependency.
Step 3: Create 1NF relations from UNF.
Therefore, the process of taking a relation from UNF to 1NF, involves resolving the multi-valued dependencies.
Method:
· Choose a primary key for the multi-valued dependancy.
· Identify the primary key of the multi-valued dependancy by underlining it or writing (PK) .
· Rewrite the DBDL by removing the paranthesis and concatenating the original primary key with the primary key of the multi-valued dependency.
· Rewrite the DBDL with the two-part Primary Key and include all the non-key attributes.
For example, using our previous report from part B, we had the following:
UNF: Customer [ CustNo, CustName, ( OrderNum, OrderDate ) ]
A. Choose a primary key for the repeating group: OrderNum would make a suitable primary key for the repeating group as it uniquely identifies the data in the repeating group.
B. Rewrite the DBDL by removing the paranthesis and concatenating the original entity name with the entity name of the multi-valued dependency.
CustOrder [ CustNo, OrderNum, CustName, OrderDate ]
NOTE: If we start with a relation that does not contain any multi-valued dependencies, it is already in 1NF.
Lab 09 Submission:
For the following User View, determine the UNF and the 1NF and hand in this page to your instructor.
Premiere Corporation Order Detail Report
Order Number
Order Date
Cust number
Part Number
Part Desc
Number Ordered
Quoted Price
Total
12489
2016-09-02
124
AX12
Iron
11
14.95
164.45
12491
2016-09-02
311
BT04
GasGrill
1
149.99
149.99
BZ66
Washer
2
399.99
799.98
12494
2016-09-04
315
CB03
Bike
4
279.99
1,119.96
12495
2016-09-04
256
CX11
Blender
2
22.95
45.90
12498
2016-09-05
522
AZ52
Dartboard
2
12.95
25.90
BA74
Basketball
4
24.95
99.80
12500
2016-09-05
124
BT04
GasGrill
3
149.99
449.97
12504
2016-09-05
522
CZ81
Treadmill
2
325.99
651.98
The answer below is what will be copied into the email. See page 1
UNF:
1NF:
Document4 by rt — 22 July 2020 1 of 1