Feature request: Alerts that work with no rows returned

[jonahgreenthal]

It seems like alerts are always based on comparing returned values to a reference point. However, I want to have alerts based on whether a query returns rows. If it returns any rows, there's a problem and the alert should be triggered. If no rows are returned, there's no problem and the alert should be considered OK.

Right now, I can write a query and set an alert, but I have to have some column used for comparison (I generally use an ID and set the alert to trigger if the ID is > 0), and when no rows are returned, the alert's status is "Unknown". So I can sort of fake the outcome I want, but in a roundabout way. It would be great if alerts based on "are any rows returned?" were a first-class citizen.