SQL Converting int to varchar

I need help converting an `integer` to a `varchar`. I'm trying to write a procedure that takes in a `ProfileID` and a `Currenttime`; using those two values it finds the start time of the `profileID` and subtracts `currenttime` from `starttime` and returns `hours:minutes:seconds`. What am I doing wrong, is there a better way to write this? Thanks. ``` CREATE PROCEDURE [dbo].[CalculateElaspedTime] -- Add the parameters for the stored procedure here @ProfileID nvarchar(10), @CurrentDateTime datetime = '' AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here if @CurrentDateTime = CAST('' as datetime) set @CurrentDateTime = GETDATE() DECLARE @StartTime datetime; DECLARE @ElaspedTime time; DECLARE @hh int; DECLARE @mm int; DECLARE @ss int; Declare @TimeString varchar set @StartTime = (Select top 1 [DateTime] From Log WHERE ProfileID = @ProfileID); set @hh = DateDiff(hour,@StartTime,@CurrentDateTime); set @mm = DateDiff(minute,@StartTime,@CurrentDateTime)-60*@hh; set @ss = DateDiff(second,@StartTime,@CurrentDateTime)-60*@mm; set @TimeString = (Select CAST(@hh as varchar)); -- Fails Here set @ElaspedTime = convert(datetime, cast(@hh as varchar) + ':' + cast(@mm as varchar) + ':' + cast(@ss as varchar)); INSERT INTO Log (ElaspedTime) Values (@ElaspedTime); END ```