The document discusses different forms of database normalization: 1) 1NF, 2NF, 3NF, BCNF normalize relations to eliminate certain types of functional dependencies that cause updating anomalies. 2) BCNF is a stronger version of 3NF where every determinant must be a candidate key. 3) 4NF eliminates multi-valued dependencies by separating relations with more than one multi-valued attribute. 5NF breaks relations into the smallest possible tables to avoid data redundancy.

2. prepaid by:prepaid by:
Hina murdhaniHina murdhani
vibhutivibhuti
savita rathodsavita rathod

3. Normalization
1NF(first
Normal
Form)
2NF(second
Normal
Form)
3NF(third
Normal
Form)
5NF(fifth
Normal
Form)
4NF(fourth
Normal
Form)
BCNF(boyce
Codd
Normal
Form)

4. BCNF(boyce-codd normalBCNF(boyce-codd normal
form)form)
 The relation is said to be in BCNF if itThe relation is said to be in BCNF if it
Is already in the third normal form.Is already in the third normal form.
 In this normal form every determinant is aIn this normal form every determinant is a
candidate key.candidate key.
 It is a stronger version of 3NF.It is a stronger version of 3NF.

5.  Scheme  {Movie Title, Movie ID, Person
Name, Role, Payment }
Key1  {Movie Title, Person Name, Role,
Payment }
Key2  {MovieID, Person Name}
Unsolved ex.( not in BCNF)Unsolved ex.( not in BCNF)

6. Both role and payment functionally depend on both
candidate keys thus 3NF
{MovieID}  {Movie Title}
Dependency between MovieID & Movie Title
Violates BCNF

7. BCNF - DecompositionBCNF - Decomposition
1.1. Place the two candidate primary keys inPlace the two candidate primary keys in
separate entitiesseparate entities
2.2. Place each of the remaining data items inPlace each of the remaining data items in
one of the resulting entities according toone of the resulting entities according to
its dependency on the primary key.its dependency on the primary key.

8. Example (Convert to BCNF)Example (Convert to BCNF)
Old SchemeOld Scheme  {M{Movie Title, MovieID,ovie Title, MovieID,
Person Name, Role, PaymentPerson Name, Role, Payment }}
New SchemeNew Scheme  {{MMovieID, PersonovieID, Person
NameName, Role, Payment, Role, Payment}}
New SchemeNew Scheme  {{Movie Title, PersonMovie Title, Person
NameName}}

9. Loss of relation {MovieID}Loss of relation {MovieID}  {Movie Title}{Movie Title}
New SchemeNew Scheme  {{Movie ID, Person NameMovie ID, Person Name,,
Role, Payment}Role, Payment}
New SchemeNew Scheme  {{Movie ID, Movie TitleMovie ID, Movie Title}}
We got the {MovieID}We got the {MovieID}  {Movie Title} relationship{Movie Title} relationship
backback
We got the {MovieID}We got the {MovieID}  {Movie Title}{Movie Title}
relationship backrelationship back

10. Fourth Form (4NF) NormalFourth Form (4NF) Normal
 To be in Fourth Normal Form,To be in Fourth Normal Form,
– a relation must first be in Boyce-Codda relation must first be in Boyce-Codd
Normal Form. Normal Form.
– a given relation may not contain morea given relation may not contain more
than one multi-valued attribute.than one multi-valued attribute.
 Mutli value dependency is a dependency inMutli value dependency is a dependency in
which determinate can determine more thanwhich determinate can determine more than
one value.one value.

11. Unsolved ex.( not in 4NF)Unsolved ex.( not in 4NF)
SchemeScheme  {{Employee, Skill, ForeignEmployee, Skill, Foreign
LanguageLanguage}}
1.1. Primary KeyPrimary Key  {Employee, Skill,{Employee, Skill,
Language }Language }
2.2. Each employee can speak multipleEach employee can speak multiple
languageslanguages
3.3. Each employee can have multiple skillsEach employee can have multiple skills
4.4. Thus violates 4NFThus violates 4NF

12. Employee Skill Language
1234 cooking French
1234 Cooking German
1453 Carpentry Spanish
1453 Cooking Spanish
2345 Cooking Spanish

13. 4NF - Decomposition4NF - Decomposition
1.1. Move the two multi-valued relations toMove the two multi-valued relations to
separate tablesseparate tables
2.2. Identify a primary key for each of the newIdentify a primary key for each of the new
entity.entity.

14. Old Scheme  {Employee, Skill, Foreign
Language}
New Scheme  {Employee, Skill}
New Scheme  {Employee, Foreign
Language}
Example( convert to 4NF)Example( convert to 4NF)
Employee Skill
1234 Cooking
1453 Carpentry
1453 Cooking
2345 Cooking
Employee Language
1234 French
1234 German
1453 Spanish
2345 Spanish

15. Fifth Normal Form (5NF)Fifth Normal Form (5NF)
 Fifth normal form is satisfied when all tablesFifth normal form is satisfied when all tables
are broken into as many tables as possibleare broken into as many tables as possible
in order to avoid redundancy. Once it is inin order to avoid redundancy. Once it is in
fifth normal form it cannot be broken intofifth normal form it cannot be broken into
smaller relations without changing the factssmaller relations without changing the facts
or the meaning.or the meaning.