A Study on the Methods of Relational Databases Transfer to Onthology

The aim of this study is to introduce the methods of transferring relational databases to ontology, classification of entering resources for transferring methods and identify the most important methods which exist in each group. In this study, bibliographic analysis was used to gather and examine papers published on transferring relational databases to ontology. Some papers are derived from paper databases and others from papers published on the Internet. After identifying the existing methods for transferring relational databases to ontology, they were classified into three groups: relational schema, conceptual data models and HTML pages of which the easiest accessible source is HTML pages which does not need cooperation of owner of the relational databases. However, since they cant be considered as real relational databases the hidden concepts in relational databases cant be derived from this source. In terms of data access, it should be noted that retrieval of all records in a relational database through the web-site is impossible. Creating conceptual model is always the first step in the process of creating database, so this model may not express the latest changes and corrections made in the database. The changes in implementation level are not usually reflected in the conceptual model. The conceptual model may not be accessible after designing and creating database. Also, some conceptual model tools do not support all features of conceptual models. Therefore, the relational schema seems to be the best source to create ontology from relational databases, when the database structure and data be accessible and owner of database is cooperative.