D'Arcy J.M. Cain wrote:
>
> Does this seem right?
>
> druid=> SELECT COUNT(*) FROM acctrans;
> count
> -----
> 0
> (1 row)
>
> druid=> SELECT client_id, SUM(tramount) FROM acctrans GROUP BY client_id;
> client_id|sum
> ---------+---
> |
> (1 row)
>
> If there are no rows in the table then shouldn't the result be no rows
> when GROUP BY is used? Further, What about this?
>
> druid=> SELECT SUM(tramount) FROM acctrans;
> sum
> ---
>
> (1 row)
>
> Shouldn't that be 0.00?
>
> What will the NUMERIC or DECIMAL types do in these situations? It
> looks like INTEGER has the same behaviour as MONEY (which tramount is.)
NUMERIC and DECIMAL will behave exactly as above, because
it's the (irritating) correct behaviour. It is handled in the
generic grouping and aggregate code (in fact none of the
aggregate functions will ever be called if there isn't
anything to count/average/sum).
To get a zero count, you need a subselect in the targetlist
(not implemented yet). Currently the only way to simulate a
subselect in the targetlist is to put the count() into an SQL
function that takes the arguments you need to build the
qualification and returns the counted number.
Jan
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