From: | <btober(at)seaworthysys(dot)com> |
---|---|
To: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: select null + 0 question |
Date: | 2003-07-14 12:24:54 |
Message-ID: | 64897.216.238.112.88.1058185494.squirrel@$HOSTNAME |
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Thread: | |
Lists: | pgsql-general |
> Jean-Christian Imbeault wrote:
>
>> Why is it that "select null + 1" gives null but "select sum(a) from
>> table" where there are null entries returns an integer?
>>
>> Shouldn't the sum() and "+" operators behave the same?
> SQL92 (6.5 <set function specification>):
> 1) Case:
> a) If COUNT(*) is specified, then the result is the cardinality of T.
> b) Otherwise, ...
> So ...
> CREATE TABLE foo (value integer);
> INSERT INTO foo VALUES (NULL);
> INSERT INTO foo VALUES (3);
> Compare:
> SELECT COUNT(*) FROM foo;
> vs.
> SELECT COUNT(value) FROM foo;
Interesting. Thanks for pointing that out. I hadn't thought about the
fact that, e.g.,
SELECT count(*), count(last_name), count(middle_name) FROM person
would produce
430, 430, 186
~Berend Tober
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