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USER'S GUIDE MORDAB A MOSTLY RELATIONAL DATA BASE

IP.com Disclosure Number: IPCOM000148963D
Original Publication Date: 1899-Dec-30
Included in the Prior Art Database: 2007-Apr-12
Document File: 24 page(s) / 1M

Publishing Venue

Software Patent Institute

Related People

Baxter, Anthony Q.: AUTHOR [+3]

Abstract

Contents Section

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Contents

I Introduction

11 Formalism for Pracessing Queries by MOBDAB

111 Syntax and Semanti es of MORDAB Query Language

IV MUTIL - MORDAB File Maintenance Utilities

V Examples

Section

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      This document describes how to use MO'RDAB, a mostly relational data base. Originally, 'MORDAB was developed as a tool to investigate problems that are encountered when using any data base. Specifically,
we were concerned with the problem of distributing a data base and with
developing a natural language interface. At present, our use of MORDAB falls into three categories. First, to give students experience in administrating and accessing a relational data base. Second, we have built a relational data base containing actual biographical and academic data about Computer Science graduate students, Third, we are investi- gating the problem of query processing on a relational data base that is "mostly" relational. That is, tuples of some relations may be missing but meaningful information can still be extracted. These features of MORDAB w i l l not be discussed in this report.

     The next section describes the properties of a relationalview of data that pertain to the implementation of MORDAB. Section I11 details the syntax and semantics of the query language of M O W . MtlTIL, a set of utility routines for maintaining the relations in a data base is described in Section IV. Finally, Section V discusses the use of MORDAB
as it is implemented on the DEC-10. 'Many examples are included to demonstrate the power and flexLbiliZy of the system.

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     NORDAB is built on the concept of a relational view of data, first described by Codd. [I]. There have been several excellent elaborations
of this description and it is not our intent to elaborate further. In- stead, the treatment given here pertains to those aspects of implementing

a relational data base system.

     Following the treatment given by Date in 12) a relation R is a subset of the cross product of the sets Dl, D2, . . . , DN. That is

RCi<dl,d

2,....e]

dl€ Dl,d2& D2,..., % '

D~}

The sets D are called the domain of R and each<dl,d2,*.., &) that belongs to R is called a tuple of R.

As an example of a relation, consider a relation called STUDHIST

which contains .the course history of students, Fig. 11.1 depicts this

relation in the form of a table which is a convenient way to view a rela- tion. The domains of this reiation

Number Course Sect ion Semester Grade

I

The relation STUDHIST

Fig. 11-1

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CRSHIST

Name Course Section Semester

BAIlTER CS570 0 2 SPRING77 CURTZ CS605 01 SPRING76 HART CS685 0 3 FALL7 5
JOWlJSON CS502 01 FALL7 6 KNU...