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SQLAdvanced#normalization
SQLIntermediate#normalization
What is normalization? Explain 1NF, 2NF and 3NF.
Normalization organises columns and tables to remove redundancy and update anomalies. 1NF: atomic values, no repeating groups. 2NF: 1NF plus no partial dependency on part of a composite key. 3NF: 2NF plus no transitive dependency on non-key columns.
Example
Not 1NF: student(id, phones = '9876,9123') 1NF: student_phone(student_id, phone) 3NF violation: order(id, cust_id, cust_city) — cust_city depends on cust_id, move it to customers.