IB Computer Science Topic A3.2.5: Differences Between Normal Forms Key Definitions

Attribute B is functionally dependent on attribute A if every value of A gives exactly one value of B. The dependency runs one way only, so A determines B does not mean B determines A.

Normalization is the process of structuring a relational database into tables so that each fact is stored in exactly one place, carried out in stages called normal forms, each of which removes one kind of dependency problem.

A partial-key dependency is a non-key attribute that depends on only part of a composite primary key rather than on the whole key. Removing every partial-key dependency is the condition for second normal form.

A transitive dependency, also called a non-key dependency, is a non-key attribute that depends on another non-key attribute instead of on the primary key. Removing every transitive dependency is the condition for third normal form.