Junction Objects in Salesforce

A custom object with two master-detail relationships. Using a custom junction object, you can model a “many-to-many” relationship between two objects.

1. The first master-detail relationship you create on your junction object becomes the primary relationship. This affects the following for the junction object records:
   

   • Look and feel: The junction object's detail and edit pages use the color and any associated icon of the primary master object.
   • Record ownership: The junction object records inherit the value of the Owner field from their associated primary master record. Because objects on the detail side of a relationship do not have a visible Owner field, this is only relevant if you later delete both master-detail relationships on your junction object.
   • Division: If your organization uses divisions to segment data, the junction object records inherit their division from their associated primary master record. Similar to the record ownership, this is only relevant if you later delete both master-detail relationships.
2. Select a Sharing Setting option. For master-detail relationship fields, the Sharing Setting attribute determines the sharing access that users must have to a master record to create, edit, or delete its associated detail records.
3. For the Related List Label that will display on the page layout of the master object, do not accept the default. Change this to use the name of the other master object in your many-to-many relationship. For example, change this toBugs so users will see a Bugs related list on the case detail page.