How to get rid of anomalies

Normalisation splits a bloated table into related tables so each fact lives once — eliminating the anomalies at their source.

• 1NF: atomic values only; no repeating groups or lists in a cell; every row unique via a key.
• 2NF: every non-key field depends on the WHOLE primary key (fixes composite-key tables).
• 3NF: no non-key field depends on another non-key field (move it to its own table).
• Result: more tables linked by foreign keys; queries JOIN them back together.
• Practical target: 3NF for operational databases; warehouses may deliberately denormalise.

• Normalisation — the step-by-step decomposition into well-formed tables.
• Functional dependency — field B is determined by field A.