Various embodiments of the present invention are directed to a database with an extensible type system for at least one user-defined type that comprises information for describing its structure as well as information for describing an inheritance relationship between itself and another user-defined type (either a subtype or a supertype/base type). For certain embodiments, the user-defined type is defined in something other than Sequential Query Language (SQL) statement such as, for example, a Common Language Runtime (CLR) statement, a statement in C, C++, and C# ("C-sharp"), and/or a visual basic statement. In any event, several embodiments are further directed to a system wherein the database is aware of the inheritance relationship between two user-defined types by an explicit registration of the user-defined types with said database.