how many region are presented on the table
select count ( * ) from region
list out the region name
select region_name from region
what is the region code of Afghanistan
select region_code from region where region_name = "Afghanistan"
what is the highest number city affected
select t1.region_name from region as t1 join affected_region as t2 on t1.region_id = t2.region_id group by t1.region_id order by count ( * ) desc limit 1