The current data models used in OODBMS (object oriented database management systems) are basically divided into two categories: traditional ‘type strong’ and non traditional ‘type weak’. The feature of the former is that the objects sharing the same structure (schema) and behaviors (methods) are grouped into a class. The schema of class to which the objects belong interprets the meaning of the objects. Therefore a class must be predefined before its objects are defined. The latter is characterized by schema-less, i.e., the meaning of the objects is 'self-describing', and hence the schema need not to be defined in advance for the objects. In this paper, after outlining the main advantages and disadvantages of these two kinds of models, the authors prove that it is necessary to find some tradeoffs between traditional 'type-strong' data models and non-traditional 'type-strong' data models and non-traditional 'type-weak' ones in order to adequately accommodate the efficient and flexible manipulation of dynamic objects. For this reason, a novel dynamic data model is proposed based on CCM (conceptual clustering mechanism) which has been successfully used for the development of an object-oriented VDBMS (video database management system).