Sunday, 25 May 2014

1NF and 2NF Comparison


Difference between 1NF and 2NF / Comparison of 1NF and 2NF / Compare 1NF and 2NF / 1NF and 2NF Comparison / 1NF and 2NF difference




Properties to be satisfied for 1NF and 2NF (recall)

1NF – All attribute values are atomic values, i.e, no repeating group or no composite attributes present.
2NF – Table should be in 1NF and no partial functional dependency presents.






Properties
1NF
2NF
Attribute Domain
Should be Atomic
Should be Atomic
Functional Dependencies Identification
Not necessary
Must
Handling of Update Anomalies
Does not handle. It deals with the basic structure of a relation.
Handle update anomalies.
Composite Key as Primary Key
Primary Key can be Composite key
Primary Key cannot be Composite key always. It may violate 2NF if partial key dependency exists. That is, no partial functional dependency is permitted
Goal
Eliminate Redundant Data
Ensure Data Dependencies




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