【摘要】 Micro SQL是微机关系数据库管理系统NITDB采用的数据语言。为了进行查询优化,本文对Kim W.的思想加以推广,从理论上提出了若干关于Micro SQL查询的等价定理,并把一些结果运用到NITDB中,从而为NITDB提供了一种查询变换优化措施,提高了查询效率。更多还原

【Abstract】 Micro SQL is a data language used in NITDB, a relationai DBMS on microcomputer. In order to optimize queries, some theorems relating to the equivalence of Micro SQL query statements are given in this paper by extending the idea presented in the paper of Kim W. Some of the results have been used in NITDB and an optimization strategy via query transformation was developed in NITDB to make query processing more efficient.更多还原