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4.25 Basic Method "Normalization" (NORM)  

  4.25 Elementarmethode "Normalisierung" (NORM)

Contents  
  • 1 Identification/Definition of the Method
  • 2 Brief Characteristic of the Method
  • 3 Limits of the Methods Application
  • 4 Specification of the Methods Allocation
  • 5 Interfaces
  • 6 Further Literature
  • 7 Functional Tool Requirements

    • 1 Identification/Definition of the Method

    /Date, 1990/ chap. 2.1

    2 Brief Characteristic of the Method

    Objective and Purpose

    The objective of method Normalization (NORM) is to generate data structures (entity types with attributes) so certain regularities or normalization rules are followed which might have the following effect:

    Operational Sequence

    A normalization of not normalized data structures (entity types with attributes) initiates a step-by-step splitting-up of these data structures and results in simpler normalized data structures, so-called normal forms.

    It is essentially differentiated between five normal forms. However, only the first three of these normal forms have a practical importance. Each "higher" normal form fulfills the regularities of the "lower" normal form.

    3 Limits of the Methods Application

    When representing and storing technical objects in tables (e. g. in geographical information systems, the design of integrated circuits, computer aided design (CAD)/computer aided manufacturing (CAM) ), the request for the first normal form often turns out to be an obstacle since objects belonging together have to be stored in several tables.

    4 Specification of the Methods Allocation

    No. Activity Description
    4.1 SD5.1
    Description of
    SW Component/
    Module/
    Database    		 At first, the present complete entity-relationship models (E/R models) always have to be normalized up to the third normal form. In exceptional cases, a denormalization might be advisable when changing to the physical storage based on performance reasons. Together with LOGM - Logical DB Modeling and DNAV - Data Navigation Modeling, the method covers that part in subproduct SW Design (Database).Schema Definition which refers to the database management system (DBMS) oriented data structure.

    The complete schema definition also requires the specification of external keys and indices as well as integrity conditions and possibly views. Furthermore, DBMS-specific storage parameters and all data elements must be completely defined.

    5 Interfaces

    No. Interface Observation Information in Annex 1
    5.1 NORM-ER Within the scope of the ER - E/R Modeling, the normalization is applied to change an E/R model comprising attributes into a normalized form. 4.12 Interface ER-NORM

    6 Literature

    /Date, 1990/ An Introduction to Database Systems,Vol.I
    /Vetter, 1990/ Aufbau betrieblicher Informationssysteme

    7 Functional Tool Requirements

    SSD09 - Supporting Information Structuring

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