Entity in DBMS
Database management systems, or DBMSs, are sizable, cohesive
data sets. They aid organizations in efficiently storing, retrieving, and
managing data, which is a crucial part of contemporary data management.
Entities are the fundamental notion that underpins all database management
systems (DBMSs). They are real-world objects or concepts stored inside
databases. With an emphasis on providing a comprehensive grasp of this
fundamental idea and its significance in database format, this article will
examine the entities sector within a DBMS.
Entity
In the actual world, an entity is a “thing” or “object”.
Attributes are characteristics that define an entity. Thus, an entity is
anything about which we have data stored. In order to be included in the
database, entities need to be able to be easily distinguished from one another.
An employee, a bank account, a student, etc. are a few
examples of entities.
Entity Set
A group of related types of entities with common attributes is called an entity set.
For Example: Every student in a school is an entity set of
Student entities.
It can be classified into two types:
Strong Entity Set
Effective sets of entities are those that can stand alone
and have unique primary keys for every instance. It exists as a separate and
independent creature.
For instance: An entity set of cars with attributes such as
the car's name, color, and registration number is a strong entity because no
two cars can have the same plate. The attributes registration number can be
thought of as the primary key, making the entity set strong.
Weak Entity Set
A weak entity requires the identification of a strong entity
in order to exist independently. Rather than having a single main key that
enables unique identification, a weak entity has a partial key.
As an instance: two automobiles may share the same color and
name, a collection of cars with similar attributes is a weak entity. As a
result, the entity set is weak since no attribute can be thought of as the
primary key.
Kinds of Entity:
There are two kinds of entities:
1. Tangible Entity:
Physical objects that are visible or touchable are referred to as entities in database management systems. A tangible entity is, in the simplest terms, anything that is physically present in the real world.
For instance, a table in a database symbolizes a tangible entity since it includes a real-world physical object that we can see and touch. It includes automobiles, watches, pens, paintings, bank lockers, mobile phones, colleges, etc.
2. Intangible Entity:
It is a non-physical item that we cannot see or touch that is referred to as an entity in DBMS. Put simply, an intangible entity is anything that does not physically exist in the real world.
For instance, even though we are unable to see or touch a bank account, it theoretically exists.
Entity Types in DBMS
· Strong Entity Types:
· Weak Entity Types:
These entities lack a fully unique identity and are
dependent on another entity for their way of life.
· Associative Entity Types:
They are those that form connections with larger entities or other entities and may possess characteristics of their own.
· Derived Entity Types:
These entities are created by a
system or computation from other entities.
· Multiple Values Entity Types:
These entities will possess
multiple values for a given attribute.
Difference between an Entity and an Entity Set
In a database management system (DBMS), every physical thing can be represented as an entity; on the other hand, an entity set is a collection of connected entities.
Every table row in a relational model—a tabular representation of data—is a distinct entity, and the table as a whole is an entity set.
Entity sets are represented by a rectangle in
entity-relationship diagrams (ER diagrams), but we are unable to express an
entity in a DBMS entity-relationship diagram.
Whereas an entity set contains the entity's blueprint, an entity itself holds the actual data.
Conclusion
The fundamental components of a database management system (DBMS) are entities, which are models of objects or ideas from the real world. They can be either powerful or weak, and they are reflected by qualities, the main key. Entities are crucial to database architecture and structured data management, together with relationships.
