Help with SQL Query - Case & Union

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Help with SQL Query - Case & Union

Author

Topic

its_me
Starting Member

6 Posts

Posted - 2012-10-12 : 13:34:20

Here is the description of my sql problem:

select distinct A, B, C
case when v.A is null THEN 'No' else 'Yes' END AS Exists_In_V,
case when '' is null THEN 'No' END AS Exists_As_C
some inner joins ….
from someTable
union
select distinct A, B, C
case when '' is null THEN 'No' END AS Exists_In_V,
case when X is null THEN 'No' else 'Yes' END AS Exists_As_C
some inner joins
from someTable1

If both the queries find a result, the data is returned is in two rows. For EX:
Col1 Col2 Col3 Exists in V Exists_As_C
A B C Yes No
A B C No Yes

Is there a way I get only 1 result record as:

Col1 Col2 Col3 Exists in V Exists_As_C
A B C Yes Yes

I first had my query without the union, because if the value is not present in one of the tables, nothing is returned. I had something like this before:

select distinct A, B, C
case when v.A is null THEN 'No' else 'Yes' END AS Exists_In_V,
case when X is null THEN 'No' else 'Yes' END AS Exists_As_C
from someTable
inner join …
and v.something = ‘xya’
left join X
and x.AC = ‘xya’

sunitabeck
Master Smack Fu Yak Hacker

5155 Posts

Posted - 2012-10-12 : 14:22:54

Since you have only pseudo-code that I cannot parse, I am not able to completely follow the logic. With my limited understanding, something like this may be what you need:

SELECT
	COALESCE(t1.A,t2.A) AS A,
	COALESCE(t1.B,t2.B) AS B,
	COALESCE(t1.C,t2.C) AS C,
	CASE WHEN t1.A IS NOT NULL THEN 'Yes' ELSE 'No' END AS Exists_In_V,
	CASE WHEN t2.X IS NOT NULL THEN 'Yes' ELSE 'No' END AS Exists_As_C
FROM
	someTable t1
	FULL JOIN someTable t2 ON
.....

its_me
Starting Member

6 Posts

Posted - 2012-10-12 : 14:44:02

Hi Sunitabeck,

I just mailed you the complete query I am working with. Thanks for the response!

Thanks!

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