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Union top 1

Posted on 2012-03-24
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Last Modified: 2012-03-28
I am using union, like.

SELECT Id, StartDate From TableA
UNION
SELECT Id, StartDate From TableB

I would like to get top 1 ordered by StartDate. How is best to do this when I use Union?
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Question by:johnkainn
2 Comments
 
LVL 12

Assisted Solution

by:sachitjain
sachitjain earned 1000 total points
ID: 37761934
Here it is

select top 1 Id, StartDate
from
      (SELECT Id, StartDate From TableA
      UNION
      SELECT Id, StartDate From TableB) L
order by StartDate
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LVL 70

Accepted Solution

by:
Scott Pletcher earned 1000 total points
ID: 37766631
This is potentially much better from a performance standpoint:


SELECT TOP 1 Id, StartDate
FROM (
    SELECT TOP 1 Id, StartDate
    From TableA
    ORDER BY StartDate
    UNION
    SELECT TOP 1 Id, StartDate
    From TableB
    ORDER BY StartDate
) AS derived
ORDER BY StartDate
0

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