How many tourist attractions are there that Alison has visited?
select count(*) from tourist_attractions as t1 join visitors as t2 join visits as t3 on t1.tourist_attraction_id = t3.tourist_attraction_id and t2.tourist_id = t3.tourist_id where t2.tourist_details = "Alison"
Please show their names.
select t1.name from tourist_attractions as t1 join visitors as t2 join visits as t3 on t1.tourist_attraction_id = t3.tourist_attraction_id and t2.tourist_id = t3.tourist_id where t2.tourist_details = "Alison"
What are the names of tourist attractions that Rosalind has visited?
select t1.name from tourist_attractions as t1 join visitors as t2 join visits as t3 on t1.tourist_attraction_id = t3.tourist_attraction_id and t2.tourist_id = t3.tourist_id where t2.tourist_details = "Rosalind"
How about the names of tourist attractions that Alison visited but Rosalind did not visit?
select t1.name from tourist_attractions as t1 join visitors as t2 join visits as t3 on t1.tourist_attraction_id = t3.tourist_attraction_id and t2.tourist_id = t3.tourist_id where t2.tourist_details = "Alison" except select t1.name from tourist_attractions as t1 join visitors as t2 join visits as t3 on t1.tourist_attraction_id = t3.tourist_attraction_id and t2.tourist_id = t3.tourist_id where t2.tourist_details = "Rosalind"