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count result appear null

Author

Topic

peace
Constraint Violating Yak Guru

420 Posts

Posted - 2013-08-26 : 04:01:26

MONTH Total Topic EndTotal
May 20 A 20
May 1000 B 2

how can i count topic='B' which is (20/1000) * 100
I get the result NULL

select *, case when topic='B' then SUM(case when topic='A' then Total end) / SUM(case when topic='B' then Total end) * 100 end
from tableA

bandi
Master Smack Fu Yak Hacker

2242 Posts

Posted - 2013-08-26 : 04:39:28

[code]SELECT c1.*, CASE WHEN c1.Topic='B' THEN sums END
FROM @tab c1
LEFT JOIN (SELECT MONTHS, SUM(CASE WHEN Topic= 'A' THEN Total END)*100/SUM(CASE WHEN Topic= 'B' THEN Total END) Sums
FROM @tab
GROUP BY MONTHS
) c2
ON c1.MONTHS = c2.MONTHS[/code]

--
Chandu

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-08-27 : 01:42:26

how will Cout B be 20/1000? as i see you've 2 as Total for B

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http://visakhm.blogspot.com/
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waterduck
Aged Yak Warrior

982 Posts

Posted - 2013-08-27 : 22:42:02

quote:
Originally posted by peace
select *, case when topic='B' then SUM(case when topic='A' then Total end) / SUM(case when topic='B' then Total end) * 100 end
from tableA

Highlighted text shows that the calculation was performed when topic = B, therefore when topic <> B, no calculation performed and no value return, therefore it return null.

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