>In your example:
>
> SELECT x.a, x.b, count(y.a) FROM t1 x, t2 y
> WHERE x.a = y.a GROUP BY x.a, x.b;
>
>Are you suggesting that if there are rows in t1 that are not in t2, that the
>count could/should be zero?
Nooooooo, the count can only be 0 if you do an outer join in this example, like:
SELECT x.a, x.b, count(y.a) FROM t1 x, outer t2 y
WHERE x.a = y.a GROUP BY x.a, x.b;
Otherwise rows with count of zero are eliminated. This is correct behavior.
Andreas