Mapping of Relational Databases to Ontology a Survey

Ontologies, the explicit and formal specification of a conceptualization, increase rapidly with the growth of the Semantic Web. However, most of data on the Web are still stored in Relational Databases (RDB). It is important to develop ways for representation of this information or to establish interoperability between RDBs and Ontologies in the Semantic Web to allow intelligent information retrieval. An effective way to achieve interoperability is finding mappings between RDB schemas and Ontologies. This paper surveys various techniques, tools and applications for mapping between RDBs and the Ontology based on certain classifications. The classifications mentioned denotes the purpose of the mapping process or the necessity to relate RDB with Ontology. This paper also reviews the discussed works with two parameters which helps to identify the purpose of the work. Apart from these classifications and given parameters there are several other parameters that can be considered in the mapping approaches.