Question

Please summarize a few of the following topics

1. normalization is DBSM

2. What is normalization

3. how to apply normalization rules to DBSM

next from all topics which is the most important ?

4. example of normalization in DBSM

Answer 1

1.) Normalization in DBMS --

• The bad database design can contain anomalies which can be bad for database administratior.
• The anomalies are as follows --
• insertion anomilies -- Trying to insert data in a record that do not exist.
• Deletion anomilies -- Try to delete record but but the related part left undeleted.
• Updation anomilies -- If you are trying to update one data item having its copies left several palces and few instances updated sucessfully and few left with old values.
• These instances cam make the datbase inconsistent.

2.) What is normalization --

• Normailization is process to minimize redudancy from set of relation.
• Redudancy in relation can contain insertion, updation and deletion. and normalization is used for mainly two purpose -- eliminating useless data and enusuring data is logically stored.
• The Normalization rules are divided into following normal forms in database --
• First Normal Form (1NF)
• Second Normal Form (2NF)
• Third Normal Form (3NF)
• BCNF
• Fourth Normal Form

3.) Apply normalizations rules to DBMS --

• First Normal Form (1NF) --
• First normal form contain single value attribute/column
• The value which is stored in the column should be of same domain
• The columns in the table should unique names
• Second Normal Form (2NF) --
• It should be in first normal forms
• and should not contain partial dependency
• Third Normal Form (3NF) --
• It is in second normal forms.
• And should not contain Transitive Dependency.
• BCNF --
• BCNF stands for Boyce and codd normal form. it is higher version of third normal form.
• And BCNF can handle the anomaly that can not be handled by 3NF.
• The 3NF table which do not contain multiple overlapping candidate keys is said to be in BCNF.
• Fourth Normal Form --
• The fourth normal form is in the BCNF form.
• and it do not contain multi-valued dependency.

4.) Example of normalization in DBMS --

• Example of 1NF --

• stud_id	stud_name	Course
  1	Amit	c1
  1	Amit	c2
  2	Mohan	c3
  3	Raju	c2
  3	Raju	c3

• Example of 2NF --
• Table -1

• stud_id	Course_id
  1	c1
  2	c2
  1	c4
  4	c3
  4	c1

• Table - 2

  • Course_id	Course_fee
    c1	4000
    c2	3000
    c3	8000
    c4	1500
    c5	8600