一个演绎工程数据库语言DEL

演绎工程数据库是工程数据库和演绎数据库集成的产物，它综合了工程数据库和演绎数据库的特点，集成了演绎数据库的查询能力和工程数据库的工程数据、对象、环境建模能力，对数据库技术的不断进步和完善有重要的理论意义和实用价值.文中分析了国内外目前在相关领域的研究现状以及出现的问题，介绍了现有数据库语言的特点及不足，提出演绎工程数据库的思路，讨论了如何扩充SQL以支持在基于逻辑的工程数据库环境下操纵各种知识，保证了其语言的易用性和与原有工程数据库的结合，对演绎工程数据库语言DEL的语法及DEL SQL实现作了详细介绍，并给出了DEL SQL语言的应用实例，验证了DEL SQL语言的适用性和正确性.

A DEDUCTIVE ENGINEERING DATABASE LANGUAGE DEL

Deductive engineering database (DEDB), which integrates the engineering database (EDB), and the deductive database (DDB), has powerful abilities of DDB's query and EDB's modeling of engineering data, objects and environment. These abilities are very important for the progress of the database technology. The research and problem in relational fields are analyzed and as a result the idea of DEDB is proposed. The characteristics and shortcomings of the present database language are introduced. Then the method is discussed on how to expand SQL to support manipulating knowledge under EDB environment based on logic to ensure the language DEL is easy to use and combine with the EDB. Furthermore, the DEL's grammar, the implementation and the instances are provided to verify the DEL SQL's validity and applicability.