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opposite of UNION ?

Posted on 2010-09-08
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Last Modified: 2012-05-10
I understand how the UNION keyword works, in that it enables one to COMBINE queries into one result set ADDITIVELY.

Is there a way to specify a query, and then TAKE AWAY the results of another query..

Eg.

"give me all schools in the extended programme"

"and then remove all that don't have an annual return done"

(the above is not easily done in one query)

We are using SQL Server 2000

many thanks!!
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Question by:zorba111
7 Comments
 
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by:cyberkiwi
ID: 33626261
INTERSECT
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by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 33626277
with sql 2000, you either use * WHERE NOT EXISTS()* WHERE NOT IN ()* LEFT JOIN ... WHERE  ... IS NULL or a temp table, and do a DELETE based on the second query ...many ways to shave the cat ..
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by:cyberkiwi
ID: 33626291
Sorry, I didn't read properly, it is EXCEPT. But that only works 2005+

The next best would be NOT IN (subquery) if you have a single column to test on, or LEFT JOIN together with WHERE T2.idcol is null to filter out the matches from the 2nd table.
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Expert Comment

by:TechTiger007
ID: 33626352
You can use "minus" to achieve this
eg.
(select * from test) minus (select * from test where result="pass")
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by:TechTiger007
ID: 33626387
Sorry I didnt see that this is about sql server. minus is for oracle
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by:SrinathKomirishetty
ID: 33626547
Try this

--If Second table contains only Annual schools info.
SELECT * FROM FirstTable
WHERE SchoolIdentifierColumn IN (SELECT SchoolIdentifierColumn FROM SecondTable)

--If Second table contains Annual schools info and other than annaul schools info
SELECT * FROM FirstTable
WHERE SchoolIdentifierColumn NOT IN (SELECT SchoolIdentifierColumn FROM SecondTable WHERE AnnualColumn=0)
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Author Comment

by:zorba111
ID: 33627889
@angell

I did it using
* LEFT JOIN ... WHERE  ... IS NULL
in combination with
* WHERE NOT EXISTS()
and
* WHERE EXISTS()

I also did it with

or a temp table, and do a DELETE based on the second query ...

so as I could check the result set agains the 2nd method.

both tallied (after a bit of tweaking) !
thank you !!
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