how many wines are made of white colored grapes?
select count(*) from grapes as t1 join wine as t2 on t1.grape = t2.grape where t1.color = "White"
which winery produced the greatest number of these wines?
select t2.winery from grapes as t1 join wine as t2 on t1.grape = t2.grape where t1.color = "White" group by t2.winery order by count(*) desc limit 1
how the top 3 wineries?
select t2.winery from grapes as t1 join wine as t2 on t1.grape = t2.grape where t1.color = "White" group by t2.winery order by count(*) desc limit 3