HI SteveS99,
Thank you for your purchase.

When you have some complexed queries our suggestion is to make a VIEW in phpmyadmin or any other database management system and see if the query is returning the right result. If the result is good you can use that query as an input ( SELECT * FROM View_name).

Also please note that there are some limitations for the editable tables

From our documentation:

Please note these limitations on editing tables with wpDataTables.

• Only one MySQL table can be edited at a time. Queries from multiple tables with joins cannot be used as an editable feature, since SQL UPDATE and INSERT statements are generated automatically, and there currenlty is no way to update multiple tables – but this problem is being investigated and pursued.
• Only MySQL tables or tables created with “Create a table manually” and “Create a table by importing data from data source” options of “Create a Table” page can be edited.
• Server-side processing MUST be turned on for front-end editing – Note: It will turn on automatically if you forget to enable it.
• MySQL Views cannot be edited properly – only one of the underlying tables can be edited if you pass the proper ID.

Best regards.