Not able to define SQL parameter on bubble - SQL query for dynamic search (multiple optional parameters)

I think that this is DBMS related and that query string is sent to the server as it is. In query string, parameters can be ? (in this case the order is important), $n (wnere n is 1, 2 …) or @paramname. The last format works with MS SQL Server.

You should provide test values for the parameters, which are used when you initialize the query. Maybe this is the reason that nothing works in your setup as in picture.