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General information Relational model
U929-J-Z125-9-76 31
Dokuschablonen 19x24 Version 7.3us für FrameMaker V7.x vom 14.02.2007 © cognitas GmbH 2001-2007
18. Oktober 2007 Stand 11:29.48 Pfad: G:\vogt\fsc\uds\Manuale\en\udsent_e\udsent.k02
2.2.2 Relational model
The relational model is based on the theoretical work of E.F. Codd, who described the
organization and manipulation of data in database systems in terms of relational algebra.
He used precisely defined terms to represent the mathematical model of his relational
theory.
The terms and concepts used in the relational model are explained below, taking as an
example the following structure of a small database:
Figure 3: Terminology used in the relational model
DEPTNO
DESIGNATION
ABT01ENT
Development
DEPARTMENT
Record element
Record element
name
Record
LOCATION
ABT02KUN
ABT03PER
ABT04REC
ABT05VER
Customer service
Personnel
Computer center
Sales
Munich
Nuremberg
Munich
Munich
Munich
Primary key
EMPNO NAME
MIT7201 Rang
CITY
MIT0206
MIT3209
MIT9018
Smith
Gerold
Strahl
Berger
Munich
Nuremberg
Freising
Munich
Ottobrunn
SALARY
DEPT. NO
MIT5011
MIT0100
Winsmann
Munich
2800
4700
3020
6200
4820
4080
ABT04REC
ABT02KUN
ABT04REC
ABT03PER
Primary key
Foreign key
EMPLOYEES