Weak Entity and Identifying Relationship in ER Diagrams
A Weak Entity in ER Diagrams is an entity type that depends on another entity for its existence and cannot exist without it. En example of a weak entity is a Student and a University, in this example, the Student is a weak entity. Since a student can’t exist without a university. Another thing to consider is that the student’s number is only identifying inside that university, so, we need a way to specify that inside our diagram. For this, we use an Weak Entity. Also, since a weak entity, cannot exist without the class it is identified by, every instance of that entity must relate to at least one of those entities. Again, for this, we use total participation.
