I have a dataset with about a million rows in and Oracle 11 db. I'd like to find rows where col1 and col2 match but have different values in col3. I'm not sure how to do this well though i can certainly write a query that never seems to finish:
select col1,col2,col3
from table tab1
where exists
(select 1
from table tab2
where tab1.col1 = tab2.col1
and tab1.col2 = tab2.col2
and tab1.col3 != tab2.col3);
I ran this and after an hour gave up waiting - I need to analyze the problems and present it to some people for figuring out how to move forward.
Thanks in any case, Jeff
A query like this will indicate which rows having the same col1, col2 have differing values in col3:
SELECT col1, col2
FROM x
GROUP BY col1, col2
HAVING MIN(col3) <> MAX(col3)
To see how many of this col1, col2 pairs are affected:
SELECT COUNT(*)
FROM (SELECT col1, col2
FROM x
GROUP BY col1, col2
HAVING MIN(col3) <> MAX(col3)
)
You may also wish to know how many duplicates there are (ie having col1, col2, col3 the same:
SELECT col1, col2, col3
FROM x
GROUP BY col1, col2, col3
HAVING COUNT(*) > 1
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