The thesis is devoted to the development of an ontology-based methodology for the retrieval of data that would allow the access of data through the use of ontology-based knowledge. Relational database technologies, without additions, do not offer the ability to judge the structure or content of the database, nor does it implement abstractions that would allow retrieving data for users other than database experts. The aim of the dissertation is to develop a methodology that allows the implementation of an ontology-based data retrieval system that provides such opportunities. Such a system uses an ontology that describes the domain and database knowledge. The user, through domain terminology and familiar concepts, creates a description of desirable data. The system interprets this description in an ontology, creates a database request for the user, validates and classifies the retrieved data and returns the result to the user. This way, realizing the abstraction of the involved data and knowledge management technologies is possible. During the development of the work, a methodology has been developed that describes the implementation of such a system. Within the framework of the methodology, several intermediate results have been achieved which are related to the implementation of the methods described in the methodology. A database and ontology linking approach, using ontology concepts as reference points for database objects, is developed. An approach has been developed to identify these interlinking concepts. Based on the concept of linking, an ontology concept hierarchy crawl is developed that allows one to gather knowledge about a linked database and build SQL queries. In this way, the methodology describes the implementation of the data retrieval approach, which is only achievable by using only the ontology core functionality.