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 Improve union query

Author  Topic 

Humate
Posting Yak Master

101 Posts

Posted - 2013-02-15 : 12:24:40
Hi All,

I'd like to know if there is a better way of producing my result set rather than using the below union:

CREATE TABLE #t1
(PKT1 INT IDENTITY (10,1),
ID INT,
ID2 INT)
CREATE TABLE #t2

(PKT2 INT IDENTITY (20,1),
ID INT,
ID2 INT)
INSERT #t1
( ID, ID2 )
SELECT 18185, NULL UNION ALL
SELECT 18165, 39875 UNION ALL
SELECT NULL, 39875 UNION ALL
SELECT NULL, 39875 UNION ALL
SELECT 18189, NULL UNION ALL
SELECT NULL, 40001 UNION ALL
SELECT 18163, NULL UNION ALL
SELECT 18495, 40011

INSERT #t2
( ID, ID2 )
SELECT 18185, NULL UNION ALL
SELECT NULL, 39875 UNION ALL
SELECT 18189, 63751 UNION ALL
SELECT 18495, 40011

SELECT * FROM #t1

SELECT * FROM #t2

SELECT *
FROM #t1
INNER JOIN #t2 ON #t1.ID = #t2.ID
WHERE #t2.ID2 IS NULL

UNION ALL

SELECT *
FROM #t1
INNER JOIN #t2 ON #t1.ID2 = #t2.ID2
WHERE #t2.ID IS NULL

UNION ALL

SELECT *
FROM #t1
INNER JOIN #t2 ON #t1.ID = #t2.ID AND #t1.ID2 = #t2.ID2


I need to join ID1 and ID2 to t2 only when one of them exists in t2, then when both ID1 and ID2 exist in t2.

Thanks in advance

James K
Master Smack Fu Yak Hacker

3873 Posts

Posted - 2013-02-15 : 13:19:33
This?
SELECT
*
FROM
#t1 t1
INNER JOIN #t2 t2 ON
(t1.ID = t2.ID AND t2.ID2 IS NULL)
OR
(t1.ID2 = t2.ID2 AND t2.ID IS NULL)
OR
(t1.ID = t2.ID AND t1.ID2 = t2.ID2);
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visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-02-15 : 14:29:56
[code]
SELECT
*
FROM
#t1 t1
INNER JOIN #t2 t2 ON COALESCE(#t1.ID,#t2.ID) = COALESCE(#t2.ID,#t1.ID)
AND COALESCE(#t1.ID2,#t2.ID2) = COALESCE(#t2.ID2,#t1.ID2)
[/code]

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

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James K
Master Smack Fu Yak Hacker

3873 Posts

Posted - 2013-02-15 : 16:03:22
quote:
Originally posted by visakh16


SELECT
*
FROM
#t1 t1
INNER JOIN #t2 t2 ON COALESCE(#t1.ID,#t2.ID) = COALESCE(#t2.ID,#t1.ID)
AND COALESCE(#t1.ID2,#t2.ID2) = COALESCE(#t2.ID2,#t1.ID2)


------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/



I don't know if that works right when #t1.ID is null and #t2.ID2 is null and the other two are not. In that case it should not evaluate to true.
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ScottPletcher
Aged Yak Warrior

550 Posts

Posted - 2013-02-20 : 15:01:25
[code]
SELECT *
FROM #t1 t1
INNER JOIN #t2 t2 ON 1 =
CASE WHEN /*(t1.ID IS NOT NULL AND t1.ID2 IS NOT NULL) OR*/ (t2.ID IS NOT NULL AND t2.ID2 IS NOT NULL)
THEN CASE WHEN (t1.ID = t2.ID AND t1.ID2 = t2.ID2) THEN 1 ELSE 0 END
ELSE CASE WHEN
(t1.ID IN (t2.ID, t2.ID2) OR t1.ID2 IN (t2.ID, t2.ID2)) THEN 1 ELSE 0 END
END
[/code]
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