SQLServer : Convert varchar date part in DateTime

DECLARE @month int
SET @month=1
DECLARE @day int
SET @day=7
DECLARE @year int
SET @year = 2004

DECLARE @dte varchar(10)
SET @dte = RIGHT(CAST('0000' + CAST(@year as varchar) as varchar), 4) +RIGHT(CAST('00' + CAST(@month as varchar) as varchar), 2) + RIGHT(CAST('00' + CAST(@day as varchar) as varchar), 2)
DECLARE @myDate datetime
SET @myDate=convert(datetime,@dte,112)
SELECT @myDate