What are the names of the tourist attractions that have only been visited once?
select t1.name from tourist_attractions as t1 join visits as t2 on t1.tourist_attraction_id = t2.tourist_attraction_id group by t2.tourist_attraction_id having count ( * ) = 1
What are the ids of those?
select t1.tourist_attraction_id from tourist_attractions as t1 join visits as t2 on t1.tourist_attraction_id = t2.tourist_attraction_id group by t2.tourist_attraction_id having count ( * ) = 1
What are the opening hours of those attractions?
select t1.opening_hours from tourist_attractions as t1 join visits as t2 on t1.tourist_attraction_id = t2.tourist_attraction_id group by t2.tourist_attraction_id having count ( * ) = 1