Which hotel has the most stayings? - oracle

Question

I am pretty new at Oracle, and I am doing some examples which I found on one of the websites to learn something new. One of the tasks is to get from tables, which hotel has the most stayings. I find this one problem realy complex and I can not solve it by myself, so I Will be happy if someone could help me with soultion and explanation why is is that way.
I understood that question in that way, that you have to connect VISITOR, VISITED, HOTEL, OWNING and OWNER tables.
To explain. OWNING table is connecting OWNERs with their HOTELs and VISITED table is connecting VISITORs with HOTEL in which they stayed.
This are my tables for that example: Pastebin link to my example.
What I have tried so far is:
SELECT visitor.id, visitor.name, visitor.surname, hotel.name
FROM visitor
LEFT JOIN visiting
ON visitor.id = visiting.tk_visitor
LEFT JOIN hotel
ON hotel.id = visiting.tk_hotel
ORDER BY hotel.id ASC;
This is connecting three tables, so I get Visitors and Hotels connected in one table, but i can't go further.
I hope that Will be able to help me, so I can learn something new on that example.
Thanks in addition!

Answer 1

which hotel has the most stayings[?]
Each visit corresponds to one row in table visited, therefore you want to count rows of visited on a per-hotel basis. That's this:
select tk_hotel, count(*) as visits
FROM visited
GROUP BY tk_hotel
If you want only the one (one of the ones) with the most visits then you can order the results by visit count, and take only the first. To get the name of the hotel instead of just its id, you should join the previous result to the hotel table:
SELECT h.name, mv.visits
FROM (
SELECT tk_hotel, count(*) as visits
FROM visited
GROUP BY tk_hotel
ORDER BY count(*) DESC
) mv
JOIN hotel h ON h.id = mv.tk_hotel
WHERE ROWNUM = 1
;
Update
If instead you want all the rows having the maximum number of visits, then that's a different kettle of fish. Here's a way to express it:
WITH visit_count AS (
SELECT tk_hotel, count(*) as visits
FROM visited
GROUP BY tk_hotel
)
SELECT h.name, vc.visits
FROM
hotel h
JOIN visit_count vc ON h.id = vc.tk_hotel
WHERE vc.visits = (SELECT MAX(visits) FROM visit_count)