Query to chck if a column exists in multiple table

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Query to chck if a column exists in multiple table

Author

Topic

aditya2010
Starting Member

10 Posts

Posted - 2010-03-29 : 01:45:24

Hi,i have 3 tables.I want to retrive data from one table say 'A'.While retriving that data from 'A',i had to write a condition to check if a column say'Col1' from 'A' exists either in other 2 tables say 'B' and 'C'.
If exists retrive 'Col1' else not.
Please help me in witing this query.

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2010-03-29 : 02:04:36

[code]SELECT *
FROM A a
WHERE EXISTS (SELECT 1
FROM (SELECT Col1 FROM B
UNION
SELECT Col1 FROM C
)t
WHERE Col1 = a.Col1)
[/code]

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

aditya2010
Starting Member

10 Posts

Posted - 2010-03-29 : 18:05:56

Thanks Vishak16.That worked.And now if i wanted to add one more condition to the above query u helped me.

Say Col2 belongs to 'A' and col2 should not be in table 'B'

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2010-03-30 : 13:18:21

do you mean this?


SELECT *
FROM A a
WHERE EXISTS (SELECT 1
              FROM (SELECT Col1 FROM B
                    UNION 
                    SELECT Col1 FROM C
                    )t
              WHERE Col1 = a.Col1)
AND NOT EXISTS(SELECT 1 FROM B WHERE Col2=a.Col2)

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

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