Program Design and Query Processing of Relational Database Under the Null Value Cireumstances[J]. Journal of Transport Information and Safety, 2001, 1(1): 47-51. doi: 10.3963/j.issn.1674-4861.2001.01.014
Citation:
Program Design and Query Processing of Relational Database Under the Null Value Cireumstances[J]. Journal of Transport Information and Safety, 2001, 1(1): 47-51. doi: 10.3963/j.issn.1674-4861.2001.01.014
Program Design and Query Processing of Relational Database Under the Null Value Cireumstances[J]. Journal of Transport Information and Safety, 2001, 1(1): 47-51. doi: 10.3963/j.issn.1674-4861.2001.01.014
Citation:
Program Design and Query Processing of Relational Database Under the Null Value Cireumstances[J]. Journal of Transport Information and Safety, 2001, 1(1): 47-51. doi: 10.3963/j.issn.1674-4861.2001.01.014
In this paper,a method to process holdplace is proposed on thebasis of the semantics of null value and the prgram design and querying policy under null value circumstances in relational database is discussed.Moreover,the fundamental operations in relational algebra with three kinds of querying operations are defined.Also,soundness and completeness in querying calculation are analysed at the end the paper.