Question

What is meant by entity type? How it is different from entity set? Illustrate by giving suitable example from accounting reality.

Answer 1

Entity Types and Entity Sets - An entity type is defined as a collection of entities, which share a common definition in terms of their attributes. Each entity type is assigned a name for its subsequent identification.

The attributes of entity type are used to describe it in the database. The values of attributes of an entity belonging to entity type are known as Entity Instance. e.g., (110001 Capital Account 4) is an entity instance and Type = 4.
An Entity Set is a collection of all entity instances of a particular entity type.The set of entities pertaining to a particular entity type share the same set of attributes. The collection of entities of a particular entity type is grouped into entity set, called the extensive of the entity type. e.g., Entity Type : Accounts Intension (or structure) of entity type.
Entity Set - Collection of entity instances of an entity type "Accounts"

Extension (or instances) of entity type-

$\begin{array}{ccc}\text{Code}& \text{Name}& \text{Type}\end{array}$
$\begin{array}{ccc}110001& \text{Capital Account}& 4\\ 221019& \text{Jain and Co}& 4\\ 221020& \text{Jayram Bros}& 4\end{array}$