This paper and paper ( Ⅱ ), aiming at the problems in the mainstream development of KDD, put forward a new academic thought that, in the knowledge discovery, the database can be restricted and deriven by the knowledge base whose structure can be in turn improved by the database. An open KDD system, KDD* , with double-base cooperating mechanism can thus be created. At the same time, the velocity, precision, and the auto-cognition of knowledge discovery can be imroved and the knowledge base is structurally equipped with the capacity of real time maintenance and to evolve by itself. This paper mainly deals with the corresponding relation between the database and knowledge base, which are the basis of double-base cooperating mechanism.