STRATEGIES FOR COMPLEX OBJECT MANAGEMENT AND ITS SQL LANGUAGE

A lot of unstructure data and composite objects are the characteristic of engineering data. In this paper， we present the strategies for complex object management and its SQL language in our own developed engineering database management system called EDBMS/2.Two kinds of new attribute type，FILE type and VAR type，are introduced to model various unstructured data.The user—define methods are adopted to manage multimedia data convinently. In EDBMS/2， a group of heterogenious records can be linked into a meaningful composite object.To facilitate the complex query in composite hierarchy，we introduced the concept of "path expression".