1. Chapter 14
Normalization
Pearson Education © 2009

2. Normalization And Database Design
Normalization: is a technique for producing a set of suitable relations that support the data requirements of an enterprise.
Characteristics of a suitable set of relations include:
the minimal number of attributes necessary to support the data requirements of the enterprise;
attributes with a close logical relationship are found in the same relation;
minimal redundancy with each attribute represented only once with the important exception of attributes that form all or part of foreign keys.
Pearson Education © 2009

3. The Process of Normalization
Normalization is a formal technique for analyzing relations based on their primary key (or candidate key) and functional dependencies.
Normalization executed as a series of steps. As normalization proceeds, the relations become progressively:
more restricted (stronger) in format
less vulnerable to update anomalies
Pearson Education © 2009

4. The Process of Normalization
1NF
2NF
3NF
BCNF
Less vulnerable to update anomalies
Stronger in format
4NF
5NF
Higher Normal
Form
Normalization

5. The Process of Normalization
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6. Normalization 1 NF Better than unnormalized 2 NF Better than 1 NF 3 NF

7. Unnormalized Form (UNF)
A table that contains one or more repeating groups.
To create an unnormalized table
Transform the data from the information source (e.g. form) into table format with columns and rows.
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8. Unnormalized Form (UNF)
ORDER_NUM
ORDER
_DATE
PART_NUM
DESCRIPTION
NUM_
ORDERD
QUOTED_
PRICE
21608
10/20/2010
AT94
Iron 11
21.95$
21610
DR93
DW11
Gas Range
Washer 1
495.00$
399.99$
21613
10/21/2010
KL62
Dryer 4
329.95$
21614
KT03
Dishwasher 2
595.00$
21617
10/23/2010
BV06
CD52
Home Gym
Microwave Oven
12.95$
150.00$
21619
21623
KV29
Treadmill
325.99$

9. First Normal Form (1NF)
A relation in which the intersection of each row and column contains one and only one value.
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10. UNF to 1NF
Nominate an attribute or group of attributes to act as the key for the unnormalized table.
Identify the repeating group(s) in the unnormalized table which repeats for the key attribute(s).
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11. UNF to 1NF Remove the repeating group by:
1- ‘flattening’ the table: Entering appropriate data into the empty columns of rows containing the repeating data. Primary key becomes the combination of primary key and redundant value.
Disadvantage: introduce redundancy in the relation.
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12. UNF to 1NF Order Order data convert to first normal form by flatting
ORDER_NUM
ORDER
_DATE
PART_NUM
DESCRIPTION
NUM_
ORDERD
QUOTED_
PRICE
21608
10/20/2010
AT94
Iron 11
21.95$
21610
DR93
Gas Range 1
495.00$
DW11
Washer
399.99$
21613
10/21/2010
KL62
Dryer 4
329.95$
21614
KT03
Dishwasher 2
595.00$
21617
10/23/2010
BV06
Home Gym
12.95$
CD52
Microwave Oven
150.00$
21619
21623
KV29
Treadmill
325.99$
Order data convert to first normal form by flatting

13. UNF to 1NF Remove the repeating group by:
2- By placing the repeating data, along with a copy of the original key attribute(s), in separate relation. The Primary key for the new relation is the combination of original primary key and redundant value.
Pearson Education © 2009

14. UNF to 1NF Order_Part Order Order data convert to first normal form
ORDER_NUM
PART_NUM
DESCRIPTION
NUM_
ORDERD
QUOTED_
PRICE
21608
AT94
Iron 11
21.95$
21610
DR93
Gas Range 1
495.00$
DW11
Washer
399.99$
21613
KL62
Dryer 4
329.95$
21614
KT03
Dishwasher 2
595.00$
21617
BV06
Home Gym
12.95$
CD52
Microwave Oven
150.00$
21619
21623
KV29
Treadmill
325.99$
ORDER_NUM
ORDER
_DATE
21608
10/20/2010
21610
21613
10/21/2010
21614
21617
10/23/2010
21619
21623
Order data convert to first normal form
by placing the repeating data, in separate relation

15. Second Normal Form (2NF)
Based on the concept of full functional dependency and composite PK.
Full functional dependency indicates that if
A and B are attributes of a relation,
B is fully dependent on A if B is functionally dependent on A but not on any proper subset of A.
Pearson Education © 2009

16. Second Normal Form (2NF)
A relation that is in 1NF and every non-primary-key attribute is fully functionally dependent on the primary key.
Pearson Education © 2009

17. Second Normal Form (2NF)
ORDER_NUM
ORDER
_DATE
PART_NUM
DESCRIPTION
NUM_
ORDERD
QUOTED_
PRICE
21608
10/20/2010
AT94
Iron 11
21.95$
21610
DR93
Gas Range 1
495.00$
DW11
Washer
399.99$
21613
10/21/2010
KL62
Dryer 4
329.95$
21614
KT03
Dishwasher 2
595.00$
21617
10/23/2010
BV06
Home Gym
12.95$
CD52
Microwave Oven
150.00$
21619
21623
KV29
Treadmill
325.99$
Any problem with
updating Part number DR93? – Need to update 2 rows
inconsistent data? Any problem if I add new row for the Part DR93, but the description is Gas Iron, or miss-spill the correct description?
Deleting row? What if you delete the order #21608 what will happen for the part AT94, will get deleted as well (loss information)
Insert new part number but without any order details? Can you do that?
Therefore, so many problem with this tables?? We need to make it in the second normal form
Is this Table in First Normal Form? (any repeating groups)
Is this table in the Second Normal Form? (what is the PK)

18. Second Normal Form (2NF)
ORDERS (ORDER_NUM, ORDER_DATE, PART_NUM, DESCRPTION, NUM_ORDERED, QUOTED_PRICE)
It contains the following functional dependencies:
ORDER_NUMORDER_DATE
PART_NUM  DESCRPTION
ORDER_NUM, PART_NUM  NUM_ORDERED , QUOTED_PRICE , ORDER_DATE , DESCRPTION

19. 1NF to 2NF Identify the primary key for the 1NF relation.
Identify the functional dependencies in the relation.
If partial dependencies exist on the primary key remove them by placing them in a new relation along with a copy of their determinant.
A 1NF relation with a primary key that is a single field is in 2NF automatically
A relation is in second normal form (2NF) if it is in 1NF and no nonkey attribute is dependent on only a portion of the primary key
or …
All nonkey attributes are functionally dependent on the entire primary key
Pearson Education © 2009

20. 1NF to 2NF
If partial dependencies exist on the primary key remove them by placing them in a new relation along with a copy of their determinant.
( ORDER_NUM,
(PART_NUM,
(ORDER_NUM, PART_NUM,
How to complete the above relations??

21. Second Normal Form (2NF)
( ORDER_NUM, ORDER_DATE)
(PART_NUM, DESCRIPTION)
(ORDER_NUM, PART_NUM, NUM_ORDERED, QUOTED_PRICE)

22. 1NF to 2NF ORDER_NUM ORDER _DATE PART_NUM DESCRIPTION NUM_ ORDERD
QUOTED_
PRICE
21608
10/20/2010
AT94
Iron 11
21.95$
21610
DR93
Gas Range 1
495.00$
DW11
Washer
399.99$
21613
10/21/2010
KL62
Dryer 4
329.95$
21614
KT03
Dishwasher 2
595.00$
21617
10/23/2010
BV06
Home Gym
12.95$
CD52
Microwave Oven
150.00$
21619
21623
KV29
Treadmill
325.99$
ORDER_NUM
ORDER
_DATE
21608
10/20/2010
21610
21613
10/21/2010
21614
21617
10/23/2010
21619
21623
PART_NUM
DESCRIPTION
AT94
Iron
DR93
Gas Range
DW11
Washer
KL62
Dryer
KT03
Dishwasher
BV06
Home Gym
CD52
Microwave Oven
KV29
Treadmill
ORDER_NUM
PART_NUM
NUM_
ORDERD
QUOTED_
PRICE
21608
AT94 11
21.95$
21610
DR93 1
495.00$
DW11
399.99$
21613
KL62 4
329.95$
21614
KT03 2
595.00$
21617
BV06
12.95$
CD52
150.00$
21619
21623
KV29
325.99$

23. Third Normal Form (3NF) Based on the concept of transitive dependency.
Transitive Dependency is a condition where
A, B and C are attributes of a relation such that if A  B and B  C,
then C is transitively dependent on A through B. (Provided that A is not functionally dependent on B or C).
Pearson Education © 2009

24. Third Normal Form (3NF)
A relation that is in 1NF and 2NF and in which no non-primary-key attribute is transitively dependent on the primary key.
Pearson Education © 2009

25. Third Normal Form (3NF) Is this table in Second Normal Form?
Does it have any functional dependency?

26. Third Normal Form (3NF)
CUSTOMER (CUSTOMER_NUM, CUSTOMER_NAME, BALANCE, CREDIT_LIMIT, REP_NUM, LAST_NAME, FIRST_NAME)
Functional dependencies:
CUSTOMER_NUM CUSTOMER_NAME, BALANCE, CREDIT_LIMIT, REP_NUM, LAST_NAME, FIRST_NAME
REP_NUM LAST_NAME, FIRST_NAME

27. 2NF to 3NF Identify the primary key in the 2NF relation.
Identify functional dependencies in the relation.
If transitive dependencies exist on the primary key remove them by placing them in a new relation along with a copy of their dominant.
The Primary key for the new relation is the determinant.
Pearson Education © 2009

28. Third Normal Form (continued)

29. Third Normal Form (3NF)
CUSTOMER (CUSTOMER_NUM, CUSTOMER_NAME, BALANCE, CREDIT_LIMIT, REP_NUM)
REP (REP_NUM, LAST_NAME, FIRST_NAME)