What is the definition of strong entity type in database?
In the context of database design, particularly within the Entity-Relationship (ER) model, a strong entity type is defined as an entity that can be uniquely identified by its own attributes without relying on any other entity.
Key characteristics of a strong entity type include:
Primary Key: A strong entity has a primary key that uniquely identifies each instance of the entity. This key is composed of one or more attributes that are sufficient to distinguish each entity instance from others.
Independence: Strong entities do not depend on other entities for their existence. They can exist independently in the database.
Attributes: Strong entities typically have their own set of attributes that describe their properties.
For example, consider a "Customer" entity in a database. Each customer can be uniquely identified by a "CustomerID" (the primary key), and the customer can exist independently of other entities, such as "Orders." Therefore, "Customer" is a strong entity type.
In contrast, a weak entity type is one that cannot be uniquely identified by its own attributes alone and relies on a "strong" entity (often through a foreign key relationship) for its