Imagine I have a single table containing a single text column, of user names. I'm trying to find user names which differ only by case.
> select count(*) from os_users 1969 > select u1.user, u2.user from os_users u1, os_users u2 where upper(u1.user) = > upper(u2.user) and u1.user <> u2.user foo|FOO FOO|foo > select user from os_users u where exists (select 1 from os_users u2 where > upper(u2.user) = upper(u.user) and u2.user <> u.user) foo|FOO FOO|foo I tried both queries above, but they are slow (almost 3s, with close to 4M steps, i.e. O(N^2)), and ideally I'd like a query returning only one row. And that's w/ or w/o a PK or UNIQUE INDEX on the one column. > select group_concat(user) from os_users group by upper(user) having count(*) > > 1 foo,FOO I did manage the above, which returns in 7ms, and get me what I want, but in aggregated form (thus needs reparsing). Is there a query that can return just foo|FOO, i.e. the pairs of mixed-case matches efficiently? Thanks, --DD
