Conceptual vs Logical Model
Data modeling is one task that confuses many modelers because of the use of different designs of modeling. Three styles of data modeling that are very popular are conceptual, physical and logical models but because of many overlapping principles, people who wish to make use of any of these models remain confused. Their confusion is further increased because of technical jargon and terminology. This article will attempt to find out differences between conceptual and logical models in simple terms so as to remove doubts from the minds of the readers.
Conceptual Data Modeling
Entity Relationship Model is the basic feature of conceptual data model. In the ERD of this model, the entities are represented as boxes while relationships are depicted in the form of diamonds. An example of relationship can be taken as customer giving order while an example of entity is all things a business might be interested in. This model was developed by Peter Chen in 1976. However, since then this model has got diluted and rarely is it used in its pure form today.
In a conceptual data model, there are also data items apart from entities and relationships. These data items are linked to entities as their attributes. Some data items that are common to all entities can be linked to many entities in the model. One feature of any conceptual data model is the use of same terminology for entities that is used in the business. Though conceptual model is relatively simple, it doesn’t remain so given the complexities of companies today. To describe the entities and their relationships in today’s context, very high level of abstraction is required in conceptual data modelling.
Logical Data Modeling
It is when IT data is to be implemented in business data that one makes use of logical data model. While there is no need to have an order while naming entities and relationships in the conceptual model, logical model necessitates taking into account organization while creating attributes. Then, one can go for surrogate keys to make it easier if foreign keys make tables look complicated. Once completed. Logical model seems to be close to physical model. However, it still has similarities to conceptual model. Logical model has primary, foreign and alternate keys but nothing in particular to a target database platform.
What is the difference between Conceptual and Logical Data Model?
• Both conceptual as well as logical data models are important for data modeling
• While conceptual data model makes communication easy with a description of data requirement, logical data model allows IT men to chip in without having to bother about database limitations.
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