Class of Queries Processed by Navigation in Network Databases

Tetsuya Furukawa, Yahiko Kambayashi

Research output: Contribution to journalArticle

Abstract

Queries in network databases are usually processed by navigation. In this paper, queries are classified according to the network structures to be retrieved to process the queries (so‐called query schemas) and the correspondence of navigational capability, the classes of network queries, and the classes of relational queries are discussed. Simple queries are those whose answers are obtained by selection and projection of connections of records. They are divided into tree queries and cyclic queries according to the cyclicity of their query schemas. Simple queries are generalized to join queries whose answers are obtained from the Cartesian product of connections of records. Basic navigation, which produces only connections of records, can process almost all the tree simple queries and queries in some class of tree join queries. Navigation with facility to compare records can process all simple queries including cyclic queries and some class of join queries. If navigation can use variables to compare with the records' values, all simple and join queries can be processed. Natural join queries in the relational model which do not include lossy join are simple queries in the network model. Most queries including the class of relational complete ones can be processed by navigation.

Original languageEnglish
Pages (from-to)25-35
Number of pages11
JournalSystems and Computers in Japan
Volume20
Issue number9
DOIs
Publication statusPublished - Jan 1 1989

Fingerprint

Navigation
Query
Join
Class
Schema
Cyclicity
Record Values
Relational Model
Cartesian product
Network Structure

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Information Systems
  • Hardware and Architecture
  • Computational Theory and Mathematics

Cite this

Class of Queries Processed by Navigation in Network Databases. / Furukawa, Tetsuya; Kambayashi, Yahiko.

In: Systems and Computers in Japan, Vol. 20, No. 9, 01.01.1989, p. 25-35.

Research output: Contribution to journalArticle

@article{7b38a4c2022e4a3d88e5002653639220,
title = "Class of Queries Processed by Navigation in Network Databases",
abstract = "Queries in network databases are usually processed by navigation. In this paper, queries are classified according to the network structures to be retrieved to process the queries (so‐called query schemas) and the correspondence of navigational capability, the classes of network queries, and the classes of relational queries are discussed. Simple queries are those whose answers are obtained by selection and projection of connections of records. They are divided into tree queries and cyclic queries according to the cyclicity of their query schemas. Simple queries are generalized to join queries whose answers are obtained from the Cartesian product of connections of records. Basic navigation, which produces only connections of records, can process almost all the tree simple queries and queries in some class of tree join queries. Navigation with facility to compare records can process all simple queries including cyclic queries and some class of join queries. If navigation can use variables to compare with the records' values, all simple and join queries can be processed. Natural join queries in the relational model which do not include lossy join are simple queries in the network model. Most queries including the class of relational complete ones can be processed by navigation.",
author = "Tetsuya Furukawa and Yahiko Kambayashi",
year = "1989",
month = "1",
day = "1",
doi = "10.1002/scj.4690200903",
language = "English",
volume = "20",
pages = "25--35",
journal = "Systems and Computers in Japan",
issn = "0882-1666",
publisher = "John Wiley and Sons Inc.",
number = "9",

}

TY - JOUR

T1 - Class of Queries Processed by Navigation in Network Databases

AU - Furukawa, Tetsuya

AU - Kambayashi, Yahiko

PY - 1989/1/1

Y1 - 1989/1/1

N2 - Queries in network databases are usually processed by navigation. In this paper, queries are classified according to the network structures to be retrieved to process the queries (so‐called query schemas) and the correspondence of navigational capability, the classes of network queries, and the classes of relational queries are discussed. Simple queries are those whose answers are obtained by selection and projection of connections of records. They are divided into tree queries and cyclic queries according to the cyclicity of their query schemas. Simple queries are generalized to join queries whose answers are obtained from the Cartesian product of connections of records. Basic navigation, which produces only connections of records, can process almost all the tree simple queries and queries in some class of tree join queries. Navigation with facility to compare records can process all simple queries including cyclic queries and some class of join queries. If navigation can use variables to compare with the records' values, all simple and join queries can be processed. Natural join queries in the relational model which do not include lossy join are simple queries in the network model. Most queries including the class of relational complete ones can be processed by navigation.

AB - Queries in network databases are usually processed by navigation. In this paper, queries are classified according to the network structures to be retrieved to process the queries (so‐called query schemas) and the correspondence of navigational capability, the classes of network queries, and the classes of relational queries are discussed. Simple queries are those whose answers are obtained by selection and projection of connections of records. They are divided into tree queries and cyclic queries according to the cyclicity of their query schemas. Simple queries are generalized to join queries whose answers are obtained from the Cartesian product of connections of records. Basic navigation, which produces only connections of records, can process almost all the tree simple queries and queries in some class of tree join queries. Navigation with facility to compare records can process all simple queries including cyclic queries and some class of join queries. If navigation can use variables to compare with the records' values, all simple and join queries can be processed. Natural join queries in the relational model which do not include lossy join are simple queries in the network model. Most queries including the class of relational complete ones can be processed by navigation.

UR - http://www.scopus.com/inward/record.url?scp=0024734755&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0024734755&partnerID=8YFLogxK

U2 - 10.1002/scj.4690200903

DO - 10.1002/scj.4690200903

M3 - Article

VL - 20

SP - 25

EP - 35

JO - Systems and Computers in Japan

JF - Systems and Computers in Japan

SN - 0882-1666

IS - 9

ER -