Knobit of Data modelling · K-513 · Skill

Recognises a join dependency kept in one entity

What it means

A three-way entity that can be rebuilt from its pairwise projections because of a cyclic business rule, kept as one entity; or the reverse, three pairwise entities joined as if the rule held when it does not.

How it is assessed

Flags the deficient case and passes the acceptable one. Deficient: Branch Channel Product as one entity, although the rule is that a branch offers every product it is authorised for through every channel it operates; one new authorisation needs a row per channel Acceptable: Three entities (Branch Channel, Channel Product, Branch Product) when the cyclic rule holds, recorded as a data rule; the three-way entity when it does not

Builds on

Explains join dependency and fifth normal formK-559 · Knowledge

Needed by

None