Recognises a nullable foreign key on a reporting join path
https://knobit.org/id/knobit/K-628
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| Context functions | Result evaluation |
|---|---|
| Knobit creation methods | AI generated, human edited |
| Knobit types | Skill |
| LCG purposes | Assessing the learner's knowledge or skill state |
| LCG purposes | Selecting an assessment task or learning activity |
| action verb | Recognises en |
| applies knowledge | Explains the connection, fan and chasm traps |
| applies knowledge | Explains referential integrity and referential actions |
| assessment criterion | Flags the deficient case and passes the acceptable one. Deficient: `fact_account_opening.branch_key` null for accounts opened online; every report by branch loses them. `loan.collections_officer_id` null until an arrears case is assigned; loans newly in arrears are missing from the workload report Acceptable: In a dimensional model, an "Unknown" or "Not applicable" member and the foreign key `NOT NULL`; in a normalised model, the nullability kept, the reporting views using outer joins, and the logical model checked against logical row 25 en |
| assessment method | skill-tests task: Loan application physical model on Snowflake (physical design anomaly skills) en |
| conforms to profile | https://oppekava.edu.ee/a/Knobitite_kirjeldamise_ja_seostamise_reeglid#LCG-KNOBIT-0.1 |
| dcterms:identifier | K-628 |
| dcterms:license | https://creativecommons.org/licenses/by/4.0/ |
| dcterms:source | Review checklist 04-physical, row 28; Howe; C&B ("Problems with ER Models"); Codd 1979 §2.3 en |
| depends on knobit | Recognises a chasm trap |
| expected result | The rows dropping out and the join to use en |
| owl:sameAs | https://bitbucket.org/reffa/ontology/id/knobit/data-modelling/06-physical/28 |
| rdfs:label | Recognises a nullable foreign key on a reporting join path en |
| schema:creativeWorkStatus | accepted |
| schema:isPartOf | Data modelling (DAMA-DMBOK2) |
| skos:altLabel | Nullable foreign key on a join path (physical model) en |
| skos:definition | A nullable foreign key that reports reach through with an inner join. Rows with a null drop out of every such report without an error: the physical form of the chasm trap (logical row 25). en |
| skos:prefLabel | Recognises a nullable foreign key on a reporting join path en |
| target object | nullable foreign key joined inner en |
Used by
| includes knobit | Designs a physical data model for the target platform without introducing anomalies |
|---|---|
| requires knobit | Design the physical data model |