There are multiple approaches for mapping from a domain ontology to a database in the task of ontology-based data access. For that purpose, external mapping documents are most commonly used. These documents describe how the data necessary for the description of ontology individuals and other values, are to be obtained from the database. The present paper investigates the use of special database concepts. These concepts are not separated from the domain ontology; they are mixed with domain concepts to form a combined application ontology. By creating natural relationships between database concepts and domain concepts, mapping can be implemented more easily and with a specific purpose. The paper also investigates how the use of such database concepts in addition to domain concepts impacts ontology building and data retrieval.
 T. R. Gruber, “A translation approach to portable ontology specifications,” Knowledge Acquisition, vol. 5, no. 2, pp. 199-220, Jun. 1993. https://doi.org/10.1006/knac.1993.1008
 M. G. Skjæveland, M. Giese, D. Hovland, E. H. Lian, and A. Waaler, “Engineering ontology-based access to real-world data sources,” Web Semantics: Science, Services and Agents on the World Wide Web, vol. 33, pp. 112-140, Aug. 2015. https://doi.org/10.1016/j.websem.2015.03.002
 E. Kharlamov, D. Hovland, M. G. Skjæveland, et al., “Ontology Based Data Access in Statoil,” Web Semantics: Science, Services and Agents on the World Wide Web, Jul. 2017. https://doi.org/10.1016/j.websem.2017.05.005
 N. Konstantinou, D.-E. Spanos and N. Mitrou, “Ontology and database mapping: a survey of current implementations and future directions,” Journal of Web Engineering, vol. 7, no. 1, pp. 1-24, March 2008.
 D. Calvanese, B. Cogrel, S. Komla-Ebri, R. Kontchakov, D. Lanti, M. Rezk, M. Rodriguez-Muro, and G. Xiao, “Ontop: Answering SPARQL queries over relational databases,” Semantic Web, vol. 8, no. 3, pp. 471-487, Dec. 2016. https://doi.org/10.3233/sw-160217
 G. Bumans, “Mapping between Relational Databases and OwL Ontologies: an example,” Computer Science and Information Technologies, vol. 756, pp. 99-117, 2010.
 C. Martínez-Cruz, J. M. Noguera, and M. A. Vila, “Flexible queries on relational databases using fuzzy logic and ontologies,” Information Sciences, vol. 366, pp. 150-164, Oct. 2016. https://doi.org/10.1016/j.ins.2016.05.022
 Y. An and T. Topaloglou, “Maintaining Semantic Mappings between Database Schemas and Ontologies,” Lecture Notes in Computer Science, pp. 138-152. https://doi.org/10.1007/978-3-540-70960-2_8
 G. Mecca, G. Rull, D. Santoro, and E. Teniente, “Ontology-based mappings,” Data & Knowledge Engineering, vol. 98, pp. 8-29, Jul. 2015. https://doi.org/10.1016/j.datak.2015.07.003
 C. D. C. Ta and T. P. Thi, “Improving the Algorithm for Mapping of OWL to Relational Database Schema,” Lecture Notes in Computer Science, pp. 130-139, 2015. https://doi.org/10.1007/978-3-319-21024-7_9
 D. Ouyang, X. Cui, and Y. Ye, “Mapping integrity constraint ontology to relational databases,” The Journal of China Universities of Posts and Telecommunications, vol. 17, no. 6, pp. 113-121, Dec. 2010. https://doi.org/10.1016/s1005-8885(09)60534-3
 K. Čerāns and G. Būmans, “RDB2OWL: A Language and Tool for Database to Ontology Mapping,” In Databases and Information Systems VI, IOS Press, 2011, pp. 139-152. https://doi.org/10.3233/978-1-60750-688-1-139
 K. Čerāns and G. Būmans, “Database to Ontology Mapping Patterns in RDB2OWL Lite,” Databases and Information Systems, pp. 35-49, 2016. https://doi.org/10.1007/978-3-319-40180-5_3
 M. A. G. Hazber, R. Li, X. Gu, and G. Xu, “Integration Mapping Rules: Transforming Relational Database to Semantic Web Ontology,” Applied Mathematics & Information Sciences, vol. 10, no. 3, pp. 881-901, May 2016. https://doi.org/10.18576/amis/100307
 B. Motik, I. Horrocks, and U. Sattler, “Bridging the gap between OWL and relational databases,” Web Semantics: Science, Services and Agents on the World Wide Web, vol. 7, no. 2, pp. 74-89, Apr. 2009. https://doi.org/10.1016/j.websem.2009.02.001