Could you list the main normal forms used in database design?

The main normal forms (NF) used in designing relational databases help eliminate redundancy and update anomalies:

1. First Normal Form (1NF) — all attributes are atomic, meaning values in columns are indivisible, and the table does not contain repeating groups.

2. Second Normal Form (2NF) — the table is in 1NF, and all non-key attributes fully depend on the entire composite key (if the key is composite).

3. Third Normal Form (3NF) — the table is in 2NF, and there are no transitive dependencies between non-key attributes (i.e., non-key attributes do not depend on each other).

4. Boyce-Codd Normal Form (BCNF) — a stricter version of 3NF, where for every functional dependency, the determinant is a key.

5. Fourth Normal Form (4NF) — eliminates multivalued dependencies when a table contains multiple independent multivalued dependencies.

6. Fifth Normal Form (5NF) — eliminates redundancy caused by joins that cannot be reconstructed from smaller tables.

In most practical cases, it is sufficient to normalize tables to 3NF or BCNF to ensure normalization and prevent anomalies.