Introduction to Many to Many relationship in Salesforce

Using Junction Object we can achieve many to many relationship in Salesforce.

What is Junction Object: A child Custom Object having two parent Object only of a master detail relationship known as Junction Object.

Considerations for Many to Many Relationship:

• Standard objects cannot be at the detail side of a custom object in a master-detail relationship.
• An object can only appear once in multilevel master-detail relationships. For example, an object which is part of one multilevel master-detail relationship can’t also be the owner of the master object in another multilevel master-detail relationship.
• You cannot create a master-detail relationship in which the User or Lead objects are at the master side of relationship.
• As per best practice, we should not have more than 10,000 child records for a master-detail relationship.
• A junction object can’t be master in another master-detail relationship.