@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix edu: <https://knobit.org/def/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix schema: <https://schema.org/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<https://knobit.org/id/task/dm-physical-postgres/I4> a edu:Question ;
    rdfs:label "I4 (1 points)"@en ;
    dcterms:license <https://creativecommons.org/licenses/by/4.0/> ;
    owl:sameAs <https://bitbucket.org/reffa/ontology/id/task/dm-physical-postgres/I4> ;
    schema:hasPart <https://knobit.org/id/register/data-modelling#I-621> ;
    schema:identifier "I4" ;
    schema:position 8 ;
    schema:text "Subtypes rolled down: person_customer and organisation_customer with no customer table, so account_holder.customer_id cannot have a foreign key (a polymorphic reference by customer_type), and the two identity sequences can hand out the same customer_id, which collides in account_holder's primary key. A customer table with the shared key is added; the subtype tables are keyed by customer_id with a foreign key to it; account_holder references customer; exclusivity is enforced by carrying the discriminator into the subtype keys or by a DQ rule."@en .

edu:Question rdfs:label "Question"@en,
        "Küsimus"@et .

<https://knobit.org/id/register/data-modelling#I-621> rdfs:label "dm-physical-postgres I4: customer subtypes rolled down with no supertype"@en .