The dynamic queries for the drop down fields should always be configured with two columns in the select query. For e.g., the correct query will be “Select locationname, locationname from servicedesklocationmaster where locationname <> ‘’ order by location name”
Important Note: The first column used in the query will be stored in the DB (you may also provide LocationID in this case), wherease the second column used in the query will be used for display purpose i.e., to show the value in the UI (ticket submit / edit page). Please configure the query as per your use case.