Stage 5: Derive the logical data model
Knobit of Data modelling · K-519 · Skill
Recognises undeclared subtype constraints
What it means
A supertype with subtypes and nothing saying whether an instance can belong to more than one subtype (disjoint or overlapping) or to none (total or partial).
How it is assessed
Flags the deficient case and passes the acceptable one. Deficient: Party → Person, Organisation, with nothing saying whether a sole trader (FIE) is one, the other, both or neither Acceptable: Stated as disjoint and total; FIE modelled as a Person with a business role; the discriminator's value set lists exactly the subtypes (`LOG-013`)
Builds on
- Explains supertype and subtype constraintsK-566 · Knowledge