Normalization in database

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3. NORMALIZATION IN DATABASES
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4. NORMALIZATION
• The process of efficiently organizing data in a
database.
• Two goals of normalization process:
 Eliminating Redundant Data
 Ensuring data dependencies
• Main objective:
 Isolate data
 Reduce the amount of database space
 Make database structure flexible
 Consistent throughout database

5. • Should not suffer from following anomalies.
 Update anomalies.
 Insertion anomalies.
 Deletion anomalies.
S_No S_name S_address Course_opted
1 smith calicut php
2 turner kannur java
3 clark wayanad java
4 smith calicut Android

6. Normalization Stages
• 1NF
• 2NF
• 3NF
• Boyce-Codd Normal Form (BCNF or 3.5NF)

7. First Normal Form (1NF)
• The values in each column of a table are
atomic .
• Each table has a primary key.
• There are no repeating groups.

8. Second Normal Form (2NF)
• Should be in 1NF.
• Remove subsets of data that apply to multiple
rows of a table and place them in separate
tables.
• Create relationships between tables.

9. Third Normal Form (3NF)
• should be 2NF.
• Has no transitive functional dependencies.
• Remove columns that are
not dependent upon the primary key.
• To convert 2NF to 3NF, we again divide tables.

10. Boyce-Codd Normal Form(BCNF)
• Should be 3NF.
• Every determinant must be a candidate key.
• All tables can have only one primary key
• Candidate Key:
 Any attribute or a set of attributes together that
has the eligibility to become a primary key.

11. TRANSFORMATION FROM UNF TO
HIGHER NORMAL FORMS USING AN
EXAMPLE
Dep_no Dep_
name
Stud_no Stud_
name
Stud_
dob
Stud_
age
Course_
name
Course_
fee
1 cse 101 Name 1 1990-1-01 23 java 5000
102 Name 2 1991-5-25 22 php 4000
103 Name 3 1992-3-01 21 Java,php 5000,
4000
2 ec 104 Name 4 1990-2-01 23 robotics 10000
105 Name 5 1991-3-01 22 circuits 15000
106 Name 6 1992-4-01 21 robotics 10000

12. Conversion to 1st Normal Form
Dep_no Dep_
name
Stud_no Stud_
name
Stud_
dob
Stud_
age
Course_
name
Course_
fee
1 cse 101 Name 1 1990-1-01 23 java 5000
1 cse 102 Name 2 1991-5-25 22 php 4000
1 cse 103 Name 3 1992-3-01 21 Java 5000
1 cse 103 Name 3 1990-2-01 21 php 4000
2 ec 104 Name 4 1991-3-01 23 robotics 10000
2 ec 105 Name 5 1992-4-01 22 circuits 15000
2 ec 106 Name 6 1990-1-01 21 robotics 10000

13. Conversion to 2nd Normal Form
Dep_no Dep_name
1 cse
2 ec
Fk_dept_id Fk_stud_id Course_name Course_fee
1 101 java 5000
1 102 php 4000
1 103 Java 5000
1 103 php 4000
2 104 robotics 10000
2 105 circuits 15000
2 106 robotics 10000
Stud_no Stud_name Stud_dob Stud_age
101 Name 1 1990-1-01 23
102 Name 2 1991-5-25 22
103 Name 3 1992-3-01 21
103 Name 3 1990-2-01 21
104 Name 4 1991-3-01 23
105 Name 5 1992-4-01 22
106 Name 6 1990-1-01 21

14. Course_
name
Course_
fee
java 5000
php 4000
robotics 10000
circuits 15000
Dep_no Dep_
name
1 Cse
2 ec
Fk_dept_no Fk_Stud_no Fk_Course_name
1 101 java
1 102 php
1 103 Java
1 103 php
2 104 robotics
2 105 circuits
2 106 robotics
Stud_no Stud_name Stud_dob
101 Name 1 1990-1-01
102 Name 2 1991-5-25
103 Name 3 1992-3-01
103 Name 3 1990-2-01
104 Name 4 1991-3-01
105 Name 5 1992-4-01
106 Name 6 1990-1-01
Conversion to 3nd Normal Form

15. Conversion To BCNF

16. Class_name Roll_no name Class_teacher
Class a 1 smith Teacher a
Class a 2 turner Teacher a
Class b 1 clark Teacher b
Class c 1 allen Teacher c
Class_name Class_teacher
Class a Teacher a
Class b Teacher b
Class c Teacher c
Class_name Roll_no name
Class a 1 smith
Class a 2 turner
Class b 1 clark
Class c 1 allen
A Case where The table is in 3NF but not in BCNF
A Case where The table is in both in 3NF and BCNF

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