Discovery of Full functional dependencies from relations has been identified as an important database analysis technique. In order to deal with information inexactness, fuzzy techniques have extensively been integrated with different database models and theories. However, the information is often vague or ambiguous and very difficult to represent in implementing the application software. This problem can be handled by getting secured information to reduce imprecise information. Null queries are queries that elicit a null answer from the database. In fuzzy object oriented database model, a theoretical framework utilizes analogical reasoning and fuzzy functional dependency or full functional dependency to answer null queries. In this paper, the concept of fuzzy functional dependency is extended to full functional dependency on similarity based fuzzy object oriented data model. In addition, a data mining algorithm is proposed to discover all functional dependencies among attributes. From this functional dependency, we shall be able to reach full functional dependency.