In the first approach of discovering drug candidates in new chemicals (drugs)-proteins (disease genes) interactions, the number of new uses for old drugs is evaluated in the proposed database application. The procedure of extracting new drug candidates from the database with SqlTool is as follows: first, to extract Gene ID and chemical ID pairs from Gene, Drug, and Disease tables; second, to extract Gene ID and chemical ID pairs in the drug candidate files searched by the extracted chemical ID; third, to extract new combinations by excluding Gene IDs nominated in the first result from Gene IDs nominated in the second result.