Data Modeling

Data modeling

£  Data modeling techniques to easily understood representations of the data flows and processes.

£  A data model can be thought of as a diagram or flowchart that illustrates the relationships between data.

Component of data model

E-R diagram

Which represents the data strucures in a pictorial form? Because the diagram is easily learned, it is valuable tool to communicate the model to the end-user.

Data documentation

This a document that describes in detail the data objects, relationships, And rules required by the database.

Basic style of data model

Conceptual data models-

Identifies the highest-level relationships between different entities. Sometimes called

Domain models, are typically used to explore domain concepts with project stakeholders

Logical Data Modeling 

Illustrates the specific entities, attributes and relationships involved in a business function. Serves as the basis for the creation of the physical data model.

Physical Data Modeling

 Represents an application and database-specific implementation of a logical data model. PDMs are used to design the internal schema of a database, depicting the data tables, the data columns of those tables, and the relationships between the tables.

Figure 1. A simple logical data model.

 

Figure 2. A simple physical data model.

3. How to Model Data

It is critical for an application developer to have a grasp of the fundamentals of data modeling so they can not only read data models but also work effectively with Agile DBAs who are responsible for the data-oriented aspects of your project.  Your goal reading this section is not to learn how to become a data modeler, instead it is simply to gain an appreciation of what is involved.

The following tasks are performed in an iterative manner: Identify entity types Identify attributes Apply naming conventions Identify relationships Apply data model patterns Assign keys Normalize to reduce data redundancy De-normalize to improve performance