Show the names of all manufacturers.
select name from manufacturers
how many products do each of them produce?
select count(*), t2.name from products as t1 join manufacturers as t2 on t1.manufacturer = t2.code group by t2.name
what are their average prices?
select avg(t1.price), t2.name from products as t1 join manufacturers as t2 on t1.manufacturer = t2.code group by t2.name