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空值数据库查询中的选择运算规则及算法
摘    要:在DEFINITE.EXIST.MAYBE三种不同操作的基础上.详细讨论了空值环境下关系数据库查询中选择运算的规则.并依据它给出了选择运算的算法.

关 键 词:空值,查询,选择

Rules and the Algorithm of Select Operation in inquiry to Relational Database Under Null Value Circumstances
Hu Chunhai, Hao Zhongxiao. Rules and the Algorithm of Select Operation in inquiry to Relational Database Under Null Value Circumstances[J]. Journal of Yanshan University, 1995, 0(3)
Authors:Hu Chunhai   Hao Zhongxiao
Affiliation:Dept. of Auto.
Abstract:Based on three different kind of operation; DEFINITE. EXIST.MAYBE. rules of select operation in inquiry to relational database under nullualue circumstances are gone into details. and the algorithm of select operation isgiven.
Keywords:null value  inquiry  select
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