When you create a JOIN view, Virtual DataPort Server creates simple JOIN condition by linking a field of one view with another view by default. You could change the JOIN condition based on your requirement. It does not have any consequences for the SQL generation. You can configure the JOIN type and JOIN strategy from available options like Inner, Left outer, Right outer and Full under the JOIN conditions of the view.
For more information, you could refer the [Creating Join Views](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/creating_views/creating_derived_views/creating_join_views#creating-join-views) section of Virtual DataPort Administration Guide.
Hope this helps !!