Entity Relationship Diagram:

An Entity relationship diagram describe the how entities such as people, jackpot concert relate to each other within a system. There ERD are composed of entities, relationships and attributes. Now we will see how entities and attributes are relationshiped with help of ERD components.

Rectangle:Entities are represented by rectangle


Double Rectangle: A weak entity is represented in the double rectangle and it is implemented by foreign key relationship with another entity. Double_rectangle

Diamond Shape: Relationship / action are represented by diamond. Diamond_shape

Ellipse /Oval: Attributes are represented by ellipses /oval Ellipse_shape

Double Ellipse: An attribute can have more than one field / value like phone number so it is represented in double ellipse. Double_ellipse

Dashed Ellipse Or Derived Attribute: Attribute which is based on another attribute are called derived attribute and they are represented by dashed ellipse. Dashed_ellipse

Lines: They are ways of showing relationship and cardinality.

Binary relationship and cardinality:

One to One : One_To_One

One to Many: One_To_Many

Many to One: Many_to_one

Many to Many: Many_to_many

Representation of Participation Constraints Total_Partial_Participation

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