Subtract two subqueries

Question

I have the following queries. I'd like to subtract the numbers from the SUMs and then return only the ones with a result other than 0. Any help would be appreciated. I would also be interested to see if this can be done in one query. I tried it with the HAVING clause but it was returning wrong results. Using SQL Server 2008

  SELECT 
(
 SELECT station_id, SUM(tcl_missing + tcl_not_missing) as tcl_total
 FROM tcl_missing_summary 
 GROUP BY station_id
) as a 

(
 SELECT station_id, SUM(total) as total
 FROM tcl_breakdown_op
 WHERE tr_standard not like '%cru'
 GROUP BY station_id
) as b
 WHERE a.tcl_total - total <> 0

Solution

assuming you have more than one stationID,

  SELECT station_id, tcl_total, total, a.tcl_total - total as diff
from (
 SELECT station_id, SUM(tcl_missing + tcl_not_missing) AS tcl_total
 FROM tcl_missing_summary 
 GROUP BY station_id
) AS a INNER JOIN

(
 SELECT station_id, SUM(total) AS total
 FROM tcl_breakdown_op
 WHERE tr_standard NOT LIKE '%cru'
 GROUP BY station_id
) AS b
ON a.stationid = b.stationid
 WHERE a.tcl_total - total <> 0

also consider something like

SELECT 
    station_id,
    SUM(tcl_missing + tcl_not_missing) AS sum_tcl_total,
    SUM(total) AS sum_total,
    SUM(tcl_missing + tcl_not_missing) - SUM(total) AS diff
FROM 
    tcl_missing_summary s INNER JOIN
    tcl_breakdown_op b ON
    s.station_id = b.station_id
WHERE
     tr_standard NOT LIKE '%cru'    
GROUP BY 
    station_id
HAVING
    SUM(tcl_missing + tcl_not_missing) <> SUM(total)