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To: pgsql-sql@postgresql.org
From: Thomas Kellerer <spam_eater@gmx.net>
Subject: Re: it's not NULL, then what is it?
Date: Wed, 01 Jul 2009 00:41:35 +0200
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	<4A4A941C.2060604@pinpointresearch.com>
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Steve Crawford wrote on 01.07.2009 00:39:
>>   canon=# select count(maf) from gallo.sds_seq_reg_shw
>>   canon-#  where maf ISNULL;
>>
> I believe count will only count not-null 

Correct

SELECT count(some_col)
FROM some_table;

is the same as

SELECT count(*)
FROM some_table
WHERE some_col IS NOT NULL;