Stage 5: Derive the logical data model
Knobit of Data modelling · K-525 · Skill
Recognises a chasm trap
What it means
A path exists, but an optional relationship on it breaks it for some instances, so they silently drop out of every query that follows the path.
How it is assessed
Flags the deficient case and passes the acceptable one. Deficient: Branch 1:N Account Manager 1:N Account with Account → Account Manager optional: accounts opened online have no path to a branch and vanish from branch totals (row 24's fix can create this) Acceptable: A direct Account → Branch relationship, or a direct-channel branch, so every account reaches exactly one
Builds on
- Explains the connection, fan and chasm trapsK-569 · Knowledge