order of clauses

create table vals (
x float,
y float
);
insert into vals values (2,4);
insert into vals values (2,2);
insert into vals values (2,1);
insert into vals values (2,0);
select x/y from vals where y>0 and x/y>1;

will give a divide by zero error as A=(y>0) and B=(x/y>1) can be evaluated in
any order (A and B = B and A). I obviously would like (y>0) to happen first,
but I don't see how this can be achieved.. Any ideas?

Cheers,

Patrick