Entity in DBMS

Database management systems (DBMS) are large, integrated collections of data. They play an important role in modern data management, helping agencies keep, retrieve, and manage data effectively. At the core of any DBMS is the concept of entities, which is a basic concept that refers to real-world devices or ideas inside a database. This article will explore the sector of entities within a DBMS, providing an in-depth understanding of this fundamental concept and its significance in database format.

Entity

An entity is a "thing" or "object" in the real world. An entity contains attributes, which describe that entity. So anything about which we store information is called an entity. Entities are recorded in the database and must be distinguishable, i.e., easily recognized from the group.

For example: A student, An employee, or bank a/c, etc. all are entities.

Entity Set

An entity set is a collection of similar types of entities that share the same attributes.

For example: All students of a school are a entity set of Student entities.

Key Terminologies used in Entity Set:

• Attributes: Attributes are the houses or traits of an entity. They describe the data that may be connected with an entity.
• Entity Type: A category or class of entities that share the same attributes is referred to as an entity kind.
• Entity Instance: An entity example is a particular incidence or character entity within an entity type. Each entity instance has a unique identity, often known as the number one key.
• Primary Key: A primary key is a unique identifier for every entity instance inside an entity kind.

It can be classified into two types:

Strong Entity Set

Strong entity sets exist independently and each instance of a strong entity set has a unique primary key.

Example of Strong Entity includes:

• Car Registration Number
• Model
• Name etc.

Weak Entity Set

A weak entity cannot exist on its own; it is dependent on a strong entity to identify it. A weak entity does not have a single primary key that uniquely identifies it; instead, it has a partial key.

Example of Weak Entity Set includes:

• Laptop Color
• RAM, etc.

Kinds of Entities

There are two types of Entities:

Tangible Entity

• A tangible entity is a physical object or a physical thing that can be physically touched, seen or measured.
• It has a physical existence or can be seen directly.
• Examples of tangible entities are physical goods or physical products (for example, "inventory items" in an inventory database) or people (for example, customers or employees).

Intangible Entity

• Intangible entities are abstract or conceptual objects that are not physically present but have meaning in the database.
• They are typically defined by attributes or properties that are not directly visible.
• Examples of intangible entities include concepts or categories (such as “Product Categories” or “Service Types”) and events or occurrences (such as appointments or transactions).

Entity Types in DBMS

• Strong Entity Types: These are entities that exist independently and have a completely unique identifier.
• Weak Entity Types: These entities depend on another entity for his or her lifestyles and do now not have a completely unique identifier on their own.

The Example of Strong and Weak Entity Types in DMBS is:

• Associative Entity Types: These constitute relationships between or greater entities and might have attributes in their own.
• Derived Entity Types: These entities are derived from different entities through a system or calculation.
• Multi-Valued Entity Types: These entities will have more than one value for an characteristic.

Conclusion

In a database management system (DBMS), entities are the fundamental components that represent the objects or concepts that exist in the real world. They are represented by attributes, the primary key, and they can be either strong or weak. Together with relationships, entities play an important role in structured data management and database design.