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Table 2 The applied rules for generating conceptual ontology (TBox)

From: A novel approach for learning ontology from relational database: from the construction to the evaluation

Patterns Kind of patterns OWL corresponding element
Table patterns Table without FK OWL: class
Table with one FK
Table with more than 2 FKs
Tables that contain exactly 2 foreign keys with presence of independent attributes
Binary Relationship table Tables that contain exactly 2 foreign keys without presence of independent attributes We create two object properties ( owl:objectProperty) The latter is an inverse of the former
Tables with one FK Attributes that are FK + NULL + Not UNIQUE Object Property + Functional Property + Min Cardinality of the inverse property = 1
Attributes that are FK + NOT NULL + NOT UNIQUE Object Property + Card = 1 + Min Cardinality of the inverse property = 1
Attributes that are FK + NOT NULL + UNIQUE Object Property + Functional Property + Functional Property for the inverse Property
Attributes that are FK + NOT NULL + UNIQUE + NOT PK (FK is not equal to the PK) Object Property + Functional Property + Card = 1 + Functional Property for the inverse Property
Attributes Attribute ( neither PK nor FK) DatatypeProperty
Attribute + NOT NULL DatatypeProperty + MinCardinality = 1
Attributes NOT FK + UNIQUE DatatypeProperty + MaxCardinality = 1
Primary Key MinCardinality + MaxCardinality = 1 (Cardinality = 1)
Check Constraint Attribute with constraint with an integer greater than 0 xsd:positiveInteger
CHECK with enumeration xsd:positiveInteger
CHECK constraint as Value Restriction Xsd:minInclusive, Xsd:maxInclusive, Xsd:minExclusive, Xsd:maxExclusive
Default constraint Attribute with Default Value Owl:hasValue
Inheritance relationship Two tables share the same primary key rdfs:subClassOf
Symmetric Relationship FK is a reference to the same table owl: SymmetricProperty
Transitive Relationship FK is a reference to the same table, but now it is accompanied by a trigger ON DELETE CASCADE OWL:TransitiveProperty
Inheritance relationship improvement The range of the foreign Key attribute Owl:AllValuesFrom
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