List all the shop names.
select shop_name from shop
List all the shop names that has stock in the shops.
select t2.shop_name from stock as t1 join shop as t2 on t1.shop_id = t2.shop_id group by t1.shop_id
Among those, keep the shop names whose open year is later than 2010
select t2.shop_name from stock as t1 join shop as t2 on t1.shop_id = t2.shop_id group by t1.shop_id having t2.open_year > 2010
List the names of shops that have more than one kind of device in stock.
select t2.shop_name from stock as t1 join shop as t2 on t1.shop_id = t2.shop_id group by t1.shop_id having count(*) > 1