Showing posts with label Data Model. Show all posts
Showing posts with label Data Model. Show all posts
Tuesday, August 7, 2012
Tuesday, May 8, 2012
Conceptual Vs Logical Vs Physical Data Model
Conceptual Vs Logical Vs Physical Data Model
We had earlier seen the different types of data models
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.
|
 |
 |
|
Related Posts
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.
Logical Data Model
Logical Data Model
The Logical data model, is a high level data model which provides details of the entities (Tables) in the model, the relationship between the entities, the attributes/properties (Columns/Fields) specific to each of the entities. At this stage the details of the Primary/Foreign key are also know hence Normalization of the tables can be done at this stage.
This model can be used during the late requirement gathering /
early design stages, at this stage we gain additional details on the attributes
specific to each of the entities, hence we can get a concrete structure of each
of the entities.
Conceptual Data Model
Conceptual Data Model
The conceptual data model is a very high level data
model which just shows the various entities (Tables) in the model and the
relation between the entities.
This data model can be used during the initial high
level design phase where the requirement clarity is restricted only to the key
entities, the details of their attributes are not known at this point in time.
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