[1]黎仁蔚.空值和N关系代数[J].东南大学学报(自然科学版),1986,16(4):67-75.[doi:10.3969/j.issn.1001-0505.1986.04.009]
 Li Renwei.Nulls and N-Relational Algebra[J].Journal of Southeast University (Natural Science Edition),1986,16(4):67-75.[doi:10.3969/j.issn.1001-0505.1986.04.009]
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《东南大学学报(自然科学版)》[ISSN:1001-0505/CN:32-1178/N]

卷:
16
期数:
1986年第4期
页码:
67-75
栏目:
本刊信息
出版日期:
1986-07-20

文章信息/Info

Title:
Nulls and N-Relational Algebra
作者:
黎仁蔚
南京工学院计算机科学与工程系
Author(s):
Li Renwei
Department of Computer Science and Engineering
关键词:
关系数据库 关系代数 集合和关系 多值逻辑 查询语言
Keywords:
relational database relational algebra set and relation multivalued logic data query language
分类号:
+
DOI:
10.3969/j.issn.1001-0505.1986.04.009
摘要:
随着关系数据库理论与实践的发展,人们越来越注意到空值问题。本文引进了三种不同语义的空值,井在此基础上,讨论了空值对关系数据库的影响,给出了空值环境下的逻辑、集合和关系代数,还讨论了N关系代数的一些性质。 N关系代可用来作为处理数据库中空值问题的抽象数据查询语言。
Abstract:
The three semantically different nulls, which are inexisting value, existing but unknown value, and placeholder, in relational database are introduced, and a detailed discussion on N-logic, N-set and N-relational algebra is given as well. In addition, some of fundamenatal properties are proved. N-relational algebra we present can serve as an abstract data query language for an incomplete relational database.

相似文献/References:

[1]周建华,胡敏强.基于关系数据库的电力变压器故障诊断系统[J].东南大学学报(自然科学版),1998,28(6):68.[doi:10.3969/j.issn.1001-0505.1998.06.014]
 Zhou Jianhua,Hu Minqiang.A Database Based Diagnostic Expert System of Transformer’s Faults[J].Journal of Southeast University (Natural Science Edition),1998,28(4):68.[doi:10.3969/j.issn.1001-0505.1998.06.014]

更新日期/Last Update: 2013-05-01