Some Consideration on the Data Model of Geometric Data Bases

This paper presents a required geometric model for mechanical parts and proposes a network + relational hybrid data model in the geometric data base system, in which the data structure is based on so called ´Complete Weak Connected Graph´ (CWCG) and some new concepts such as ´Entity Type´, ´Representation Type´ and ´Entity´ are put forward. In addition, we introduce a ´Set record´ into a set to describe the semantic relation among records. We are trying to make the data model capable of reflecting the real world more exactly and more convenient to use.