Chapter 2 Data Models (BUSSINESS RULES AND INTRO OF MODEL) - Coggle…
Data Models (BUSSINESS RULES AND INTRO OF MODEL)
• Descriptions of a certain organization's policies, methods, or principles — This category includes any organisation that keeps and uses data to generate information.
• Describes the operations that are used to develop and enforce actions within an organization's environment.
• It must be documented and kept up to date.
• It must be simple to comprehend and widely distributed.
• Describe the qualities of data from the company's perspective.
Discovering Business Rules
• Sources of business rules:
– Company managers
– Policy makers
– Department managers
– Written documentation
• Operations manuals
– Direct interviews with end users
• Allow designers to understand the type, role, and scope of data
• Allow designers to understand business processes
• Allow designers to define suitable relationship participation rules and limitations
• Allow designers to understand the nature, role, and scope of data
Translating Business Rules into
Data Model Components
In most cases, nouns become entities.
• Verbs transform into relationships between entities • Relationships are bidirectional • Two inquiries to determine the sort of relationship:
How many B instances are linked to one A instance?
– How many A instances are linked to one B instance?
WHAT IS MODEL ?
Data models define how the logical structure of a database is modeled. Data Models are fundamental entities to introduce abstraction in a DBMS. Data models define how data is connected to each other and how they are processed and stored inside the system.
The very first data model could be flat data-models, where all the data used are to be kept in the same plane. Earlier data models were not so scientific, hence they were prone to introduce lots of duplication and update anomalies.