Not sure if this will help you, TTL. There is a table in NPM database that stores triggered alerts, that is AlertLog table. If you are looking to just see the alert for Node object, you may filter it based on ObjectType nad include the columns you want to see. This is what I currently have just to see the alertname happened for a node object, a beginner SQL query.
Select AlertLog.LogDateTime as AlertTime, AlertDefinitions.AlertName as AlertName, AlertLog.ObjectName as NodeName, AlertLog.Message as Alert
From Alertlog
INNER JOIN AlertDefinitions ON Alertlog.AlertdefID=AlertDefinitions.alertdefid
Where AlertLog.ObjectType = 'Node' AND AlertLog.Message = 'Alert Triggered'
Order by AlertLog.LogDateTime DESC
You may use the COUNT to see the number of time it happened for particular time. WHERE clause will also help to focus on Object Name.