mysql select unique row

Question

I have the following table - mytable :

----id----|----user_id----|----value-----|
----1-------------1------------- 9
----2-------------1------------- 8
----3-------------2 -------------11
----4-------------2-------------12
----5-------------3-------------11
----6-------------4-------------8
----7-------------1-------------3

I want to SELECT * FROM mytable... where value has a single record like this:

----id----|----user_id----|----value-----
----1-------------1-------------9
----4-------------2-------------12
----7-------------1-------------3

Note that value 8 and value 11 have duplicates and I removed all

Answer 1

Try this

SELECT * FROM mytable
GROUP BY `value`
HAVING count(*) = 1

or

SELECT * FROM mytable
GROUP BY `value`
HAVING count(*) < 2

Answer 2

You could try a left join:

SELECT T1.id, T1.user_id, T1.value
FROM yourtable T1
LEFT JOIN yourtable T2
ON T1.value = T2.value
AND T1.id <> T2.id
WHERE T2.id IS NULL

Answer 3

The below query should work fine for the question asked above..

SELECT T1.* FROM MYTABLE T1, ( SELECT VALUE FROM MYTABLE GROUP BY VALUE HAVING COUNT(*)=1 ) T2 WHERE T1.VALUE = T2.VALUE;

Regards, Venk

Answer 4

I would do this:

select t1.* 
from table1 t1
where 1 = (select count(t2.id)
                    from table1 t2
                    where t1.value = t2.value 
                    )

Hope it works.

PS: id has to be the unique key.