Difference Between Conceptual and Logical Model
Data modeling confuses many modelers, mainly because different designs of models are used. Three styles of modeling data, which are quite popular, are conceptual models, physical and logical. Between them, there exist many overlapping principles; therefore, those who want to enjoy any of these design models remain troubled. Their confusion is further increased by the use of the technical terminology. This article will attempt to discover the differences between logical and conceptual models in easy terms so as to remove the confusions from the minds of readers.
Conceptual data modeling:
The fundamental characteristic of conceptual data model is the Entity relationship model. In this model, the ERD, the different entities are represented as boxes while the relationships are represented in the form of diamonds. A sample of relationship can be taken as the customer gives an order. However, entity is an example of all things that is like a business. Peter Chen created this model in 1976. However, this model was diluted and it is rarely used in its pure form today.
In a conceptual data model, there are other items of data except the entities and relationships. These data items are related to entities such as their attributes. Some data items that are common to all the entities can be linked to many other entities in the model. A characteristic of any conceptual data model is the use of common terminology for entities that is utilized in business. Although the conceptual model is quite easy, it does not remain so given the complexities and requirements of today’s companies. A very high level of abstraction is required in the conceptual design to explain the entities and their relationships in today’s context.
Logical data modeling:
We use the logical data model when IT data has to be implemented in business data. In the conceptual model, there is no need to maintain order when naming entities and relationships. In contrast, in the logical model, there is a need to organize the attributes as they are created. Therefore, you can go for replacement keys, which will make it easier if the foreign keys tables seem complicated. Once accomplished, the logic model appears to be close to the physical model. Yet it still has many similarities with the conceptual model. The logic model has primary keys, foreign keys and alternatives, but nothing in particular to a platform of target database.