How to do a Rollup in SQL Server?

I am trying to complete a Rollup on MS SQL so that my column "DET" has a complete sum at the last row. The Arrive column contains characters so if possible I'm just trying to have the total row in that column be NULL. When I did Group by Date, DET, Arrive with Rollup it makes subtotals, adding up the totals of each date (which I don't want if possible).

Select Date = isnull(Date,'Total'), DET, Arrive = isnull(Arrive, 'Total') from
    (select convert(VARCHAR, EventDate1, 112) as Date,
    sum(CASE WHEN Depart = 'DET' and (ETStatus = 'F' or ETStatus = 'L' or ETStatus = 'C') THEN 1 ELSE 0 END) as DET, Arrive
    from TicketCoupons
    where EventDate1 >= '20160601' and EventDate1 <= '20160709'
    group by convert(VARCHAR, EventDate1, 112), Arrive
    )mytable
    where PIT > '0'
    group by Rollup(Date), DET, Arrive
    order by Date

Also, I'm new to SQL and I'm aware that my code is likely disorganized, so I apologize in advance. I appreciate the help!

Solution

note: it is unclear where PIT is sourced, so it is not in the answer below.

You can do this with grouping sets instead:

select 
      [Date]= isnull(convert(varchar(8), EventDate1, 112),'Total')
    , DET = sum(case 
                when Depart = 'DET'and ETStatus in ('F','L','C') 
                  then 1
                else 0
                end)
    , Arrive= Arrive
  from TicketCoupons
  where EventDate1 >= '20160601'
    and EventDate1 <= '20160709'
  group by grouping sets (
      (convert(varchar(8), EventDate1, 112), Arrive)
    , ()
  )
  order by [Date]

The proper way to handle null values in this case is to use grouping() return 'Total' instead of null when using grouping sets:

select 
      [Date]= case when grouping(convert(varchar(8), EventDate1, 112)) = 0 
                  then 'unknown' -- values of null will return as 'unknown'
                else 'Total' -- total row will return 'Total' as requested
                end
    , DET = sum(case 
                when Depart = 'DET'and ETStatus in ('F','L','C') 
                  then 1
                else 0
                end)
    , Arrive= case when grouping(Arrive) = 0
                  then 'unknown' -- values of null will return as 'unknown'
                else null -- total row will return `null` as requested
                end
                */
  from TicketCoupons
  where EventDate1 >= '20160601'
    and EventDate1 <= '20160709'
  group by grouping sets (
      (convert(varchar(8), EventDate1, 112), Arrive)
    , ()
  )
  order by [Date]

reference: