Get total in HH:MM format from the dataset
===

    CREATE procedure St_Proc_GetUserReportforCurrentDayTask                        
	@userID int                        
	as                        
		Begin                        
			set NoCount on;                        
			DECLARE @TODAY DATE                          
			SET @TODAY = CONVERT(VARCHAR(10), GETDATE(), 111)                        
			select  CONVERT(VARCHAR,production.CalendarDate,101) + RIGHT (CONVERT(VARCHAR,production.CalendarDate , 100 ) ,7) as Date,                         
			RegionAndProjectInfo.RegionProjectName as Region ,                        
			County.CountyName as County,                        
			WorkType.WorkTypeName as WorkType,                        
			Task.TaskName as Task,            
			Production.VolumeProcessed as 'Volumes Processed',                        
			Production.TimeSpent as 'Duration'                        
			from Production                         
			inner join RegionAndProjectInfo                        
			on                        
			RegionAndProjectInfo.RegionProjectID=Production.RegionProjectID                        
			inner join County                        
			on                         
			County.CountyID=Production.CountyID                        
			inner join WorkType                        
			on                        
			WorkType.WorkTypeID=Production.WorkTypeID                        
			inner join Task                        
			on                        
			Task.TaskID=Production.TaskID                        
			where Production.UserID=@userID and CalendarDate >= @TODAY                        
		End 

From the above Stored Procedure i am filling a Dataset.After that i am binding this Dataset to a grid view.
In the dataset ,the Column Duration contains Data in HH:MM Format(example-01:00,12:45,02:59 etc).Is there a way that i can get the total of Duration in HH:MM format from the dataset itself.I dont want to query again from the Database to get the Sum of the Duration.
