I don't think you can as the SQL has a binding to the DB connection you have selected for the data adapter. You might have to write a BR and use LINQ to join two tables as suggested in the following post
https://community.onestreamsoftware.com/t5/Workflow-and-Data-Integration/Join-Framework-table-data-to-Application-table-data-using-SQL/m-p/4262#M300
Here is a nice example of LINQ join queries
https://docs.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/linq/how-to-combine-data-with-linq-by-using-joins
