Query to retrieve aggregated data using variables
Something like this?

declare @EarliestDate datetime
declare @LatestDate datetime
declare @NumberOfEvents int
declare @EventInfo nvarchar(100) = 'Summary of events'

SELECT   @EarliestDate = (SELECT MIN(Dtm) FROM [YourTable]) 
        ,@LatestDate = (SELECT MAX(Dtm) FROM [YourTable]) 
        ,@NumberOfEvents = (SELECT COUNT(*) FROM [YourTable]) 

SELECT   @EventInfo [Title]
        ,@EarliestDate [Earliest Date]
        ,@LatestDate [Latest date]
        ,@NumberOfEvents [Number of Events]