Sql Normalization — Free Sql Tutorial
Learn Sql Normalization in Sql with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
TL;DR: Learn Sql Normalization in Sql with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
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Sql Normalization in Sql
Normalisation is the process of organising a database to reduce data redundancy and improve data integrity. The rules are called Normal Forms (NF).
1NF: Each column must have atomic (indivisible) values. No repeating groups. Each row must be unique. No multi-value columns like "Maths,Science,English" in one cell.
2NF: Must be in 1NF + every non-key column must depend on the ENTIRE primary key (no partial dependencies). This applies when you have a composite primary key.
3NF: Must be in 2NF + no transitive dependencies — non-key columns must not depend on other non-key columns. E.g., if you have student_id → dept_id → dept_name, move dept_name to a departments table.
Sql Normalization — Syntax
-- BAD: violates 1NF (multiple values in subjects) -- student_id | name | subjects -- 1 | Priya | Maths,Science,English -- GOOD: 1NF (separate rows or table) -- student_id | name | subject -- 1 | Priya | Maths -- 1 | Priya | Science -- GOOD: 3NF (separate departments table) -- students: id, name, dept_id -- departments: dept_id, dept_name, dept_head
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