Class 5 - Normalization

Data Models : We can use following models to design our database.
Entity, Hierarchical, Network

DATA MODELING :

1 – 1 Relationship
1 – many
Many – many


1-1 defining with primary – unique key
Students table (studenntID) - Hostel (StudID)

1- many definign Primary – Foreign Key
Students table (StudentID) - Library (StudID)

Many – Many defining with 3 table
Students table (studID) - Subjects (SubjectID) - Third table ( )



NORMALIZATION :

1NF
Eliminate Repeating Groups - Make a separate table for each set of related attributes, and give each table a primary key.
2NF
Eliminate Redundant Data - If an attribute depends on only part of a multi-valued key, remove it to a separate table.
3NF
Eliminate Columns Not Dependent On Key - If attributes do not contribute to a description of the key, remove them to a separate table.
BCNF
Boyce-Codd Normal Form - If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.
4NF
Isolate Independent Multiple Relationships - No table may contain two or more 1:n or n:m relationships that are not directly related.
5NF
Isolate Semantically Related Multiple Relationships - There may be practical constrains on information that justify separating logically related many-to-many relationships.
ONF
Optimal Normal Form - a model limited to only simple (elemental) facts, as expressed in Object Role Model notation.
DKNF
Domain-Key Normal Form - a model free from all modification anomalies.