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The enhanced entity?relationship (EER) model (or extended entity?relationship model) in computer science is a high-level or conceptual data model incorporating extensions to the original entity?relationship (ER) model, used in the design of databases.

Here ERD or ER models are used through a defined set of symbols such as ovals, diamonds, rectangles, etc., and connecting lines to display the interconnectedness between them. ER Diagrams are also used in conjunction with Data Flow Diagrams (DFD), to show the flow of information within processes or systems.

An entity relationship diagram (ERD), also known as an entity relationship model, is a graphical representation that depicts relationships among people, objects, places, concepts or events within an information technology (IT) system.

What steps are required in the development of an ER diagram? Identify, analyze, and refine the business rules. Identify the main entities, using the results of Step 1. Define the relationships among the entities, using the results of Steps 1 and 2.

You read the diagrams first from left to right and then from right to left. In the case of the name-address relationship in following figure, you read the relationships as follows: names can be associated with zero or exactly one address; addresses can be associated with zero, one, or many names.

Enhanced entity-relationship diagrams are advanced database diagrams very similar to regular ER diagrams which represent requirements and complexities of complex databases. It is a diagrammatic technique for displaying the Sub Class and Super Class; Specialization and Generalization; Union or Category; Aggregation etc.

ERDPlus. ERDPlus is an online ER diagram modeling tool that supports MySQL, SQL Server, Oracle, IBM DB2, and other DBMSs. This ERD tool uses Crow's Foot notation and lets you generate SQL DDL files to create your physical database from the physical data model.