Howdy, Steve.
SELECT id
FROM dummy a
NATURAL JOIN (
SELECT fkey_id,name
FROM dummy
GROUP BY fkey_id,name
HAVING COUNT(*) > 1 AND SUM(id) = (MAX(id) + MIN(id)) * (MAX(id) - MIN(id) + 1) / 2
) b
ORDER BY id;
The GROUP BY clause is to associate records that have the same fkey_id and name
The COUNT(*) > 1 eliminates the situations when there is just one.
Now, about the equality, now i am thinking and maybe it is a bazooka to kill a fly. :)
In your table you just have duplicates? Or you may have triplicates? And quadruplicates? And in general n-uplicates? At the time, I thought you might have n-uplicates, so I designed the query to be as general as possible to handle all that cases, from which duplicates are a particular case, but now i am wondering if you don't have more than duplicates.
Well, anyway the idea is as follows
The sum of a sequence is given by first + last / 2 * n, with n = last - first + 1, OK ?
So, if the set of ids is sequencial, its sum must equal that expression. It's basically that.
But I am now wondering now that I might have misunderstood what your requests were...
If you just have duplicates, then maybe it is cleaner to substitute that clause by something simpler, like MAX(id) - MIN(id) = 1
I dunno if I fully answered your questions, but if I didn't feel free to ask
Best, Oliveiros
--
We are going to have peace even if we have to fight for it. - General Dwight D. Eisenhower
Teremos paz, nem que tenhamos de lutar por ela
- General Dwight D. Eisenhower
