A data model is simply a diagram that displays a set of tables and the relationship between them. This helps in understanding the purpose of the table as well as their dependency. A data model applies to any software development that involves the creation of database objects to store and manipulate data. This includes transactional systems as well as data warehouse systems. The data model is being designed through three main stages; they are – conceptual data model, logical and physical data model in this order.
A conceptual data model is just a set of square shapes connected by a line. The square shape represents an entity, and the line represents a relationship between the entities. This is very high level and highly abstract, and key attributes should be here.
The logical data model expands the conceptual data model by adding more detail to it and further identifies it as key attributes and non-key attributes. Hence, key attributes or attributes that define the uniqueness of that entity, such as in the time entity, it’s the date that’s a key attribute. It also considers the relationship type, whether it is one to one or one to many or many to many.
The physical data model looks a little similar to a logical data model; however, there are significant changes. Here entities will be replaced by tables, and attributes will be referred to as columns. So tables and columns are words specific to a database, whereas entities and attributes are specific to a logical data model design, so a physical data model always refers to these as tables and columns. It should be database technology compatible.
Posted Date:- 2021-10-26 10:54:19
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