Answer: – E-R stands for entity relationship. E-R diagram is a symbolic relationship among entity and relationship. The entity relationship (E-R) data models is based on a perception of real world which consists of a set of basic objects. The E-R model was introduced by P.P. Chen. He introduced not only E-R model but also corresponding diagramming techniques. The E-R model consists of entity, attribute, relationship, and key attributes components.
The E-R model uses the following symbols –
Rectangle: – This symbol represent entity set.
Oval: – This symbol represents attributes.
Diamond: – The diamond symbol represent relationships among entity sets as well as between entity and attributes.
Line: – This symbol links attributes to entity sets and entity sets to relationship.