  Constructing ontologies from relational databases is an active research topic
in the Semantic Web domain. While conceptual mapping rules/principles of
relational databases and ontology structures are being proposed, several
software modules or plug-ins are being developed to enable the automatic
conversion of relational databases into ontologies. However, the correlation
between the resulting ontologies built automatically with plug-ins from
relational databases and the database-to-ontology mapping principles has been
given little attention. This study reviews and applies two Prot\'eg\'e
plug-ins, namely, DataMaster and OntoBase to automatically construct ontologies
from a relational database. The resulting ontologies are further analysed to
match their structures against the database-to-ontology mapping principles. A
comparative analysis of the matching results reveals that OntoBase outperforms
DataMaster in applying the database-to-ontology mapping principles for
automatically converting relational databases into ontologies.
