It can be identified uniquely by considering the primary key of another entity.
For that, weak entity sets need to have participation.
Example For example, in a University database, we might have entities for Students, Courses, and Lecturers.
Students entity can have attributes like Rollno, Name, and Dept ID.
It may contain entities with attribute sharing similar values.
Entities are represented by their properties, which also called attributes. For example, a student entity may have a name, age, class, as attributes.It was proposed by Peter Chen in 1971 to create a uniform convention which can be used for relational database and network.He aimed to use an ER model as a conceptual modeling approach.An entity can be place, person, object, event or a concept, which stores data in the database.The characteristics of entities are must have an attribute, and a unique key.Entity relationship diagram displays the relationships of entity set stored in a database.In other words, we can say that ER diagrams help you to explain the logical structure of databases.There are several notations that are used in the universities, but most common one's area Chen and Crow notation.Any tool, such as Visio or Gliffy can be used to create diagrams based on Crow notation.A lecturer from the specific department takes each course, and each lecturer teaches a various group of students. We can often identify relationships with verbs or verb phrases.Relationship is nothing but an association among two or more entities. For example: A weak entity is a type of entity which doesn't have its key attribute.