Re: How to find double entries

On Wed, 16 Apr 2008, Andreas <maps(dot)on(at)gmx(dot)net> writes:
> how can I find double entries in varchar columns where the content is
> not 100% identical because of a spelling error or the person
> considered it "looked nicer" that way?
>
> I'd like to identify and then merge records of e.g. 'google',
> gogle', 'guugle'
>
> Then I want to match abbrevations like 'A-Company Ltd.', 'a company
> ltd.', 'A-Company Limited'
>
> Is there a way to do this?
> It would be OK just to list candidats up to be manually checked
> afterwards.

You can try something similar to below example. (levenshtein(text, text)
function is supplied by fuzzystrmatch module.)

SELECT T1.col, T2.col
FROM tbl AS T1,
INNER JOIN tbl AS T2
ON T1.col <> T2.col AND
levenshtein(T1.col, T2.col) < (length(T1.col) * 0.5)

Regards.