【摘要】 本文主要分析和讨论微机关系数据库管理系统NITDB的查询处理子系统QPSS在设计和实现中的一些问题,提出一套适合微机环境的具有多重优化的查询处理方法。文中介绍了本系统的查询处理过程,讨论了所采用的查询变换优化、限制条件优化和存取策略选择三步优化处理另外还简要地讨论了空值处理以及视图处理等有关问题,介绍了一些实现技术。最后,针对微机环境中的查询处理问题,提出了一些作者的看法。更多还原

【Abstract】 Some problems emerging from the design and implementation of the query processing subsystem QPSS of the relational micro-DBMS NITDB are presented and analyzed in this paper. A query processing method with multioptimization suitable especially for microcomputers is suggested. In addition to a brief introduction to the process of the query processing in the system, optimization through query transformation, optimization through preprocessing qualification and optimization through access strategy selection are discussed. Besides, null value processing, view processing and some other problems are briefly discussed as well, and a number of implementation techniques arc presented. At last, some authors’ views on the query processing in the environment of microcomputers are given.)更多还原