Understanding normalization concept
Database normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity.
Normalization entails organizing the columns (attributes) and tables (relations) of a database to ensure that their dependencies are properly enforced by database integrity constraints.
Side effects
Side-effects may arise in relations that have not been sufficiently normalized:
Update anomaly (change may need to be applied to multiple records; if update partially successful – data inconsistency appears)
Insertion anomaly (all attributes should be filled during insertion; if not – data integrity compromised)
Deletion anomaly (deletion of data representing certain facts necessitates deletion of data representing completely different facts)
Normalization Forms
UNF - Unnormalized form
1NF - First normal form
Each sell to be Single valued
Entries in a column are same type
Rows uniquely identified (add Unique ID or add more columns to make unique)
2NF - Second normal form
1st normal form
All attributes (Non-Key Columns) dependent on the key
3NF - Third normal form
2nd normal form
All fields (columns) can be determined Only by the Key in the table and no other column
4NF - Fourth normal form
3rd normal form
No multi-valued dependencies
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