What are the different cities, and states that have invoices?
select distinct billing_city, billing_state from invoices;
What are the number of invoices for each city and state?
select billing_city, billing_state, count(*) from invoices group by billing_city, billing_state;
Also provide the total invoice!
select billing_city, billing_state, count(*), sum(total) from invoices group by billing_city, billing_state;
Can you how just the total invoice for the city Chicago in state IL?
select sum(total) from invoices where billing_city = "Chicago" and billing_state = "IL";