| 空值数据库查询中的选择运算规则及算法 |
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| 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．
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| 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 |
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| Authors: | Hu Chunhai Hao Zhongxiao |
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| Institution: | Dept. of Auto. |
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| 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. |
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| Keywords: | null value inquiry select |
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