From: Osvaldo Rosario Kussama <osvaldo.kussama@gmail.com>
To: Jeff Frost <jeff@frostconsultingllc.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: finding columns that have three or fewer distinct characters
Date: Wed, 05 Mar 2008 15:46:59 -0300
Message-ID: <47CEEAA3.3040004@gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0803050912570.4804@discord.home.frostconsultingllc.com>
References: <Pine.LNX.4.64.0803050912570.4804@discord.home.frostconsultingllc.com>
Jeff Frost escreveu:
> I've got an interesting one...I'm trying to find columns that have three
> or fewer distinct characters (for example, "aaaaaaaaaa"). Wondering if
> I need to write a function or if someone has an idea how to do it with
> built in functions and/or pattern matching?
>
> I think the thing to do would be to lowercase everything, then remove
> all duplicate chars and spaces, then use length() on that, but it's not
> obvious to me how I might remove the duplicate chars with the pattern
> matching support in the docs.
>
Try:
SELECT
array_to_string(array(
SELECT DISTINCT lower(substr('aabbcdddef AB',i,1))
FROM generate_series(1,length('aabbcdddef AB'))
s(i))
, '');
Osvaldo
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To: pgsql-sql@postgresql.org
Cc: osvaldo.kussama@gmail.com, jeff@frostconsultingllc.com
Subject: Re: finding columns that have three or fewer distinct characters
In-Reply-To: <47CEEAA3.3040004@gmail.com>
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