d. Data Extraction
In this step we extract record from database and add to the ontology. For this extraction we need to deploy query, create instance and create property. These are as follow: Mapping between data extracted from database and ontology I done through instance. Instance use to maps data extracted using query and classes then used to deepen the ontology. Instance creation requires class, queries, merge string, actual data and rename option. Class and queries should be created before instance creation. Ontology creation totally depends on instance and instances are compiled before conversion and return zero on failure and n rows on successful. If instance have error then ontology is created with zero field. Properties combine two instances with a object or data relationship. Relationship should be created be forehead property creation, and it basically connect two classes. Final ontology is stored in OWL file format. Below is subset of generated ontology.
http http://www.semanticweb.Org/laptop/food.owl#Purchased_lunch — >