Unit 8 : Database Normalization

Question 1

What is normalization?

Answer 1

1. The process on evaluating and correcting table structures to minimize data redundancies

Question 2

List out the normalization forms ( 3 )

Answer 2

1. First normal form ( 1NF )
   
   • Table format
   • No repeating groups and PK identified
2. Second normal form ( 2NF )
   
   • 1NF and no partial dependencies
3. Third normal form ( 3NF )
   
   • 2NF and no transitive dependencies
4. Boyce-Codd normal form ( BCNF )
   
   • Every determinant is a condidate key ( Special case of 3NF )
5. Fourth normal form ( 4NF )
   
   • 3NF and no independent multivated dependencies

Question 3

List out the best , better and ok normalization forms

Answer 3

1. 3NF ( Best )
2. 2NF ( Better )
3. 1NF ( Ok )

Question 4

Which normalization form is the highest normalization process for most business database design purposes?

Answer 4

1. 3NF

Question 5

What is not always most desirable in normalization?

Answer 5

1. Highest level of normalization

Question 6

What is the characteristics of normalization? ( 3 )

Answer 6

1. Each table represents a single subject
2. No data item will be unnecessarily stored in more than one table
3. All attributes in a table are dependent on the primary key

Question 7

How to convert from UNF to 1NF?

Answer 7

1. Repeat group
   
   • Derives its name from the fact that a group of multiple entiries of same type can exist for any single key attribute occurrence
2. Relational table must not contain repeating groups
3. Normalizing table structure will reduce data redundancies
4. Normalization is three-step procedure

Question 8

What are the first step to convert from UNF to 1NF?

Answer 8

1. Eliminate the repeating groups
   
   • Present data in tabular format, where each cell has single value and there are no repeating groups
   • Elimate repeating groups, eliminate nulls by making sure that each repeating group attribute contains an appropriate data value