@Royi:en realidad, creo que debería ser
select customers.customerId , count(orders.id) as num
from customers join orders on custumers.Id = orders.customerId
group by customers.customerId
having num=2
@Royi:en realidad, creo que debería ser
select customers.customerId , count(orders.id) as num
from customers join orders on custumers.Id = orders.customerId
group by customers.customerId
having num=2
