Stage 5: Derive the logical data model
Knobit of Data modelling · K-518 · Skill
Recognises an entity identified only by a system-assigned key
What it means
The entity's only identifier is a number the system assigns, and nothing the business uses to tell instances apart is recorded as `natural_key`. Nothing then stops the same thing being recorded twice. A surrogate key is a physical decision in this skill. A specific form of row 17.
How it is assessed
Flags the deficient case and passes the acceptable one. Deficient: Party with `primary_key: [Party Id]` and no `natural_key`; the same company registered twice under two ids Acceptable: `primary_key` and `natural_key` on the business identifier (registry code, personal identification code); where none exists, say so and record the duplicate-matching rule as a data rule with an enforcement
Builds on
- Explains natural keys, surrogate keys and key stabilityK-568 · Knowledge