Named Query exception Handle

Hi, I am trying to fetch data corresponding to selected alarm. It works good, as soon as it finds data from the Named Query-> Table. But if data is not found it gives error message. I looked all the way to handle exception in Named Query, but could not find any.
Q1. Is it possible to suppress error message?
Q2. In the ‘Alarm Class’ instead of showing integer value, is it possible to to show corresponding ‘High’, ‘Low’, ‘Medium’… ?( I am using groupConcat({Root Container.Alarm Status Table.selectedAlarms}, “Priority”, “/”) to fetch value in Alarm Status Table.

In the Authoring page, I just had to select Scalar Query for Query type option. This solved my problem…