ER Diagram to Relational Schema - This ERD was first developed by Peter Chen in 1976. And perfected by Charles Bachman and James Martin on the basic principles of ERD. The ERD diagram is a tool for how to visualize the results of interconnected information. Entity diagrams can be places, objects, classes, and people. In the E-R Diagram, entity starts on the rectangle. For example Create an organizational chart. Managers, Employees, Departments, Products and others are considered as an entity of an Organization.
First look at entity relationship diagrams like flow diagrams. it is a special symbol. From the meaning of the symbol he is unique. Image The entity relationship diagram (ERD) shows the relationship between the set of entities stored in the database. Entities in this segment are data components. The term is an ER diagram showing the logical structure of the database.
When we want to document the system, Need a system of several ways to improve understanding of the system. The use of ERD diagrams is usually simultaneously with data flow diagrams in a data store to display. With this ERD diagram we can help visualize the connected data in general. ER diagram is very useful for us in making a rational database.