Essay Using Physical Data Design in Organisation-Relationship Analysis

organisation-relationship analysis consists of three major abstractions to explain data. These are characteristics, organisations and relationships.

Here organisations are distinct things in the enterprise. The relationship is the relation between the attributes and organisations are the nature or residential or commercial properties of the organisations. We then model all interactions between the objects within the organisation sets by relationships or relationship sets. This makes information analysis difficult because it is needed to create models of things that do not physically exist as single items. There are 2 major parts in the organisation-relationship scenario. They are Conceptual information modeling and Physical data modeling.

The Physical Data Model defines the physical execution of the database. With the Physical Data Model, we think about the details of the real physical application. It considers both software or information storage structures. We can modify the PDM to fit our efficiency or physical constraints.

The Physical Data Model fills the following functions:

• Represent the physical company of information in a graphic format
• Generate database creation and modification scripts
• Define referential stability activates and restrictions
• Create extended attributes
• Reverse engineer existing databases
• Regenerate a Conceptual Data Model
• Physical Data Model development

There are a number of ways to create a Physical Data Model:

• Create a Physical Data Model from a Conceptual Data Model
• Develop a Physical Data Model from scratch
• Reverse engineer a database into a Physical Data Model
• Objects in a Physical Data Model

A Physical Data Model graphically represents the interaction of the following things:

• Table: Collection of rows (records) that have actually associated columns (fields).
• Column: Data structure which contains an individual information product within a row (a record), the model equivalent of a database field.
• Main secret: Column or columns whose worths uniquely identify a row in a table.
• Foreign secret: Column or columns whose worths depend on and migrate from the main type in another table.
• Index: Data structure that is based upon an essential and that speeds access to information and controls unique values.
• Recommendation: Link between the main key and the foreign secret of different tables.
• View: Data structure that results from a SQL inquiry which is constructed from data in several tables.

We then design all interactions between the things within the organisation sets by relationships or relationship sets. This makes information analysis difficult since it is required to produce designs of things that do not physically exist as single objects. With the Physical Data Model, we consider the details of the real physical application. It takes into consideration both software or data storage structures. We can customize the PDM to suit our performance or physical constraints.