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
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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