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Total Participation and Partial participation.

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Total Participation and Partial participation.

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written 8.1 years ago by |

**Participation Constraint:**

Determines whether the existence of an entity depends on its being related to another entity through the relationship.

i. **Total Participation:**

- The participation is total if an entiy’s existence requires the existence of an associated entity in a particular relationship.
Example

An employee MUST work for a department.

An employee entity can exist only if it participates in a WORKS_FOR relationship instance

Thus its participation is TOTAL

ii. **Partial Participation:**

- The participation is partial for the vice versa.
Example

Only some employees manage departments

The participation is PARTIAL.

A formal constraint: (m, n) where m, n are number of times

- Constraint:(min, max) where m, n are min and max number of times an entity participates in a relationship instance.
- For example, (0,10) means partial participation, and (1,max) means total participation.
- Some instances of the WORK_FOR relationship:
- ln relationship set, it is natural to expect that each employee works in at least one department and that each department has at least one employee.
- This means that the participation of both Employees and Departments in WORKS_FOR is total.
- But now only some employees can manage department not all. This means that the participation of both Employees and Departments in WORKS_FOR is partial.

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