Data Modelling Terminology
Data Modelling is the diagrammatic representation showing how the entities are related to each other. It is the initial step towards database design. We first create the conceptual model, then logical model and finally move to the physical model. Generally, the data models are created in data analysis & design phase of software development life cycle. There are three types of data models – conceptual, logical and physical. The level of complexity and detail increases from conceptual to logical to a physical data model. Conceptual model will be just portraying entity names and entity relationships. Figure 1 shown in the later part of this article depicts a conceptual model. Logical model will be showing up entity names, entity relationships, attributes, primary keys and foreign keys in each entity. Figure 2 shown inside question#4 in this article depicts a logical model. Physical data model will be showing primary keys, foreign keys, table names, column names