Re: it's not NULL, then what is it?

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;