Conceptual Vs Logical Vs Physical Data Model

Conceptual Vs Logical Vs Physical Data Model

We had earlier seen the different types of data models

Conceptual Data Model

Logical Data Model

Physical Data Model

We shall now see the comparison between these models.

Conceptual Data Model	Logical Data Model	Physical Data Model
Very high level data model	High level data model	Low level data model
Only Entities (Tables) are defined	Entities & Attributes (Tables & Columns) are defined	Entities,  Attributes & Properties (Tables, Columns, Data Types & Size are defined)
Developed during the initial requirements phase of the project.	Developed during the late requirement / early design phases of the project.	Developed during the final design phase of the project.
Remains constant across databases	Remains constant across databases	Varies based on the target database.
Used to give a high level picture to the Business users.	Used by the Database administrators to Normalize and optimize the database.	Used more by the developers to develop the application.

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Conceptual Data Model

Logical Data Model

Physical Data Model

Physical Data Model

Physical Data Model

 
The Physical data model, is a low level data model, which provides all details about the entities (Tables), their attributes/properties (Columns), the size and type of each of the attributes (Data Types / Length of the Columns)

The Conceptual and Logical data models are fixed irrespective of the database used, since they define entities/attributes at a high level, however when it comes to the physical data model, it will vary based on the target database since the data types are not consistent across all the databases.

This model is built at the later stages of the design phase where all details with respect to the entities and attributes are clear, this will be the final data model based on which the development phase will progress.