I have union query as:
SELECT A, B
FROM X
UNION ALL
SELECT A,B
FROM Y

I want to further SUM(B), GROUP BY A of above union result.

How can I do this in one query?

Thanks,

Try:


SELECT A, SUM(B) FROM

(
SELECT A, B
FROM X
UNION ALL
SELECT A,B
FROM Y ) C

GROUP BY A ;

Thanks Thanks

Sometimes for better performance you might want to do multiple sums as it will be less data stored in memory for the final sum. I have had pretty good success with this in the past. Such as:

SELECT A, SUM(B) FROM

(
SELECT A, sum(B)
FROM X
GROUP BY A
UNION ALL
SELECT A,sum(B)
FROM Y
GROUP BY A) C

GROUP BY A ;