What are Mapping and Participation Constraints in DBMS?

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Mapping Constraints :-

Mapping constraint एक data constraints है जो entity के number को express करती है जिससे एक अन्य entity की एक relationship के मध्य में relate हो सकती है|

Binary relationship set के लिए या entity set A और B के  लिए चार(four) mapping constraints  हो सकते हैं|

1. One to One :-

In one to one mapping an entity in A is associated with at most one entity in B and an Entity in B is associated with at most one entity in A.

2. One to Many :-

In one to many mapping an entity in A is associated with any number of entity in B and an entity in B is associated with at most one entity in A.

3. Many to One :-

In many to one mapping an entity in A is associated with at most one entity in B and an entity in B is associated with any number of entities in A.

4. Many to Many :-

In Many to Many mapping an entity in A is associated with any number of entities in B is associated with any number of entities in A.

Participation Constraint:

Relationship set में भाग लेने वाली entity पर participation constraints लागू होता है।

Participation Constraint ये दो प्रकार के होते हैं:

  1. Total Participation – Entity Set में प्रत्येक entity को relationship में भाग लेना चाहिए। यदि प्रत्येक student को किसी course में enroll करना है, तो student की total भागीदारी होगी। ER diagram में कुल participation को dual line द्वारा दिखाया गया है।
  2. Partial Participation – Entity Set में entity relationship में part ले भी सकती है और नहीं भी। यदि कुछ courses किसी भी student द्वारा enrolled नहीं हैं, तो course की participation partial होगी|

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