Answer» - ONE to One(1:1) – For each instance, in the first entity, there is one and only one in the second entity and VICE versa. LIKE - Employee Name and Employee ID, One employee can have only one Employee ID and one Employee ID can be allocated to one person only.
- One to Many(1:N) – For each instance, in the first entity, there can be one or more in the second entity but for each instance, in the second entity, there can be one and only one instance in the first entity. Like - Manager & Employee, One Manager can have many employees but one employee can have only one Manager.
- Many to Many(N:N) –For each instance, in the first entity there can be one or more instance in the second entity and vice versa. Like – Employee & Project, One Employee can work on MULTIPLE projects and One Project can have multiple employees to work.
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