Question

What are the major components in the E - R Diagrams.

Answer 1

Hey there!

E - R diagrams :

-- E - R Diagrams stands for Entity Relationship Diagrams.

-- It is a way of express the logical structure of a database

-- The structure are expressed graphically .

⇒ An E -R diagram consists of the following major components :

--  Retangles : It is divided into two parts.

1. Entity set.
2. Attribute set.

-- Undivided rectangles : It represents the attributes of a relationship set and attributes of an entity set that are part of the primary key are underlined.

-- Diamonds : It represents the relationship set.

-- Double diamonds : It identify the relationship sets linked to weak entity set (comes under entity set).

-- Lines : It links the entity set to relationship set.

-- Double lines : In a relationship set, it indicate total participation of an entity.

-- Dashed lines : In a relationship set, it links the attributes of a relationship set.