find the number of all products from each manufacture. list each company's name.
select count(*), t2.name from products as t1 join manufacturers as t2 on t1.manufacturer = t2.code group by t2.name
show the average price of each company’s products.
select avg(t1.price), t2.name from products as t1 join manufacturers as t2 on t1.manufacturer = t2.code group by t2.name