What are name of all the roller coasters?
select name from roller_coaster
Give me their length.
select name,length from roller_coaster
Show me the roller coasters that are longer than 3000.
select name,length from roller_coaster where length > 3000
How many countries do not have any of them?
select count(*) from country where country_id not in ( select country_id from roller_coaster where length > 3000 )