← DBMS & SQL learning pathDBMS & SQL · Module 8 of 10
Normalization
Organise tables to remove duplicate data and update problems.
📖 Key ideas
- Normalization splits data into tables to reduce redundancy.
- 1NF: atomic values, no repeating groups.
- 2NF: 1NF and no partial dependency on part of a composite key.
- 3NF: 2NF and no transitive dependency (non-key depends on non-key).
- It prevents insert, update and delete anomalies.
💡 Real-life example: Instead of writing a teacher's phone number on every student's card, keep one teacher card and refer to it.
RedundancySame data stored many times
1NFAtomic values, no repeating groups
3NFNo transitive dependencies
AnomalyProblem when inserting, updating or deleting