WTParts without WTDocuments in Query Builder

Hi,

We would like to make a report to get WTParts that are not associated with any WTDocument (WTParts without WTDocumets). We want to do something similar to a Left Join or Inner Join but with Query Builder.

Is there any possibility to do this kind of Joins in Query Builder or Are there any examples of Sub selects that try to replicate this?

Thank you!