It aids you in joining to other tables or an alias of the same table (self-join) having foreign keys. For example...
1. Open a worksheet on, say, the HR schema.
2. Click on the Query Builder tab
3. Drag & drop the Employees table there.
4. Using the link icon, you can specify either an Oracle join type, or default to the ANSI join type, then join on Employees (self-join employee to manager).
5. To make things more interesting, drag & drop Departments in too.
6. Then the link icon with the focus on Employees will also allow creation of inter-table joins on Department_Ids / Employee/Manager / Manager/Employee
Thanks for the detailed explanation... When I followed your steps using a connection to an ODS with little to no referential constraints, I only saw the join type context item. However, when I switched to an OLTP schema that includes extensive RI constraints, the functionality came to life! Makes sense now.
Thanks again for taking the time!