how many wines are made from Zinfandel grapes?
select count(*) from wine where grape = "Zinfandel"
What are the average prices and number of cases for these wines?
select avg(price), avg(cases) from wine where grape = "Zinfandel"
only show numbers for the ones produced in 2009.
select avg(price), avg(cases) from wine where year = 2009 and grape = "Zinfandel"