I need to count raw data from deliveries, to aggregate all recipients
who were sent, clicked and opened an email. I need to present these
metrics based on the country of the recipient, not the country of the
campaign that sent the email. So individual recipients have received
more than one delivery, but i don't care, I just need to aggregate the
recipients by country and then calculate the open rates and click rates.
So the question here is how to aggregate, based on primary key the
number of em...