It can define as an abstract and conceptual representation of data. This was first described in the year 1976 by Dr. Peter Chen Properly and it was appeared in a paper in the first issue of the ACM publication, "Transactions on Database Systems". When concern about the Entity-Relationship Approach it consists of an analytical method and consists with modeling technique. In today's world it recognized as one of the most important tools in the data administration tool kit. When we go through the Entity relationship diagram we can identify that, E-R Diagrams use mainly three symbols to represent the relationship among entities.
Entity: A real-world item or concept that exists on its own. Here we can define an entity type as a rectangle containing the type name
Attribute: An Attribute
is a characteristic of an Entity; they are properties used to distinguish one entity instance from another. Attribute is represented by an clipcy.
Relationship: As an association between two entities to which all of the occurrences of those entities must conform which is represented by a diamond
We can summarized the main advantages of this entity relationship diagram can be define as follows,
- All the major components of the information environment are formally represent
- The major relationships of data have been formally recognized
- Aids to maintain good and consistent naming standards
- Visualize representation