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Friday, September 28, 2012

Data Modeling - Conceptual, Logical, And Physical Data Models


The three level of data modeling, conceptual data model, logical data model, and physical data model, were discussed in prior sections. Here we compare these three types of data models. The table below compares the different features: 



Feature
Conceptual
Logical
Physical
Entity Names
 
Entity Relationships
 
Attributes
 
 
Primary Keys
 
Foreign Keys
 
Table Names
 
 
Column Names
 
 
Column Data Types
 
 


Below we show the conceptual, logical, and physical versions of a single data model.

Conceptual Model Design






Logical Model Design 

 

Physical Model Design

 
 We can see that the complexity increases from conceptual to logical to physical. This is why we always first start with the conceptual data model (so we understand at high level what are the different entities in our data and how they relate to one another), then move on to the logical data model (so we understand the details of our data without worrying about how they will actually implemented), and finally the physical data model (so we know exactly how to implement our data model in the database of choice). In a data warehousing project, sometimes the conceptual data model and the logical data model are considered as a single deliverable.


Ref : http://www.1keydata.com/datawarehousing/data-modeling-levels.html


njoy the simplicity.......
Atul Singh

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