Knobit of Data modelling · K-511 · Skill

Recognises a non-superkey determinant in a 3NF entity

What it means

An attribute or set of attributes determines another but is not a candidate key. Usually hides behind overlapping composite keys, so the entity is in 3NF and still has update anomalies.

How it is assessed

Flags the deficient case and passes the acceptable one. Deficient: Arrears Assignment (Loan, Product Family, Collections Officer), key (Loan, Product Family); each officer works on one product family, so moving an officer means updating every assignment Acceptable: Collections Officer holds its Product Family; Loan Collections Assignment (Loan, Collections Officer); the constraint lost by the split goes to row 15

Builds on

Explains Boyce-Codd normal formK-557 · Knowledge

Needed by

None