Using SUM function on columns from two tables in a join

[liquorvicar]

I am trying to sum two separate columns from two separate columns in one query.
So I have

t1

id - value

1 -10
2 - 20
3 - 15
4 - 40
5 -100

t2

id - parent_id - value

1 - 1 - 15
2 - 2 - 5
3 - 3 - 0
4 - 4 - 30
5 - 5 - 5
6 - 5 - 5

I'd like to get the results sum(t1.value)=185, sum (t2.value)=60 but when I run this query:

SELECT sum(t1.value),sum (t2.value) FROM t1 LEFT JOIN t2 ON t1.id=t2.parent_id

I get sum(t1.value)=285, sum (t2.value)=60, i.e. it's counting t1.value twice for t1.id=5 as this appears twice in t2.parent_id.

Can anyone help, or must I use two queries?

[Piranha]

I don't think that you can do it without subqueries. But this should work (untested).

SELECT (SELECT sum(t1.value) from t1), (SELECT sum(t2.value) from t2);

I think you are better off using 2 subqueries though.