Its existence is not dependent on any other entity.įor example, Professor is a strong entity −Įvery table has one Primary key and cannot have null values. It has weak entities that are dependent on strong entity. It mainly depends on other entities, for example, dependents of a professor. The weak entity in DBMS does not have a primary key and are dependent on the parent entity. The attribute value gets stored in the database. Let us first see what it consists of − EntityĮntity in DBMS can be a real-world object with an existence, For example, in a School database, the entities can be Teachers, Students, Courses, etc.Įntities has attributes, which can be considered as properties describing it, for example, for Teachers entity, the attributes are Teacher_Name, Teacher_Address, Teacher_Subject, etc. ER Diagram displays the relationships of entity sets. It was introduced in 1976 by P.P.Chen and is known as ER Diagram, E R Model, etc. Entity-Relationship Diagram views real world as entities.
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