php - Doctrine 1.2 calculating the sum of oneToMany relations with DQL

Using doctrine 1.2 I'm trying to do the following.:

lets say I have a model Job which has many Invoice(s).

In my invoice model I have a DQL event listener like

public function preDqlSelect(Doctrine_Event $event)
{
    $q = $event->getQuery();
    $q->addSelect('(hours * local_rate) as invoice_payout');
    $q->addSelect('(hours * global_rate) as invoice_bill');
    $q->addSelect('((hours * global_rate) - (hours * local_rate)) as invoice_profit');
}
Copy code

which works fine, also to note the above is calculated as needed because depending on the user asking for it, it needs to be calculated differently.

The issue I am having is trying to do something like the following:

Select Job and foreach job->invoices SUM('invoice_payout) as job_payout, SUM('invoice_bill) as job_bill, SUM('invoice_profit') as job_profit.

I know the above is in no way correct syntax, but it was the best way I could explain what I was after.