USER'S GUIDE MORDAB A MOSTLY RELATIONAL DATA BASE
Original Publication Date: 1899-Dec-30
Included in the Prior Art Database: 2007-Apr-12
Software Patent Institute
Baxter, Anthony Q.: AUTHOR [+3]
11 Formalism for Pracessing Queries by MOBDAB
111 Syntax and Semanti es of MORDAB Query Language
IV MUTIL - MORDAB File Maintenance Utilities
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.
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
dl€ Dl,d2& D2,..., % '
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
The relation STUDHIST
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...