mysql - 在 MySQL 中加入 2 个 sql 查询

Question

我正在尝试在一个查询中加入 2 个 sql 查询。

第一个获取每家酒店的房间数。 第二个获取酒店入住客人的数量。 我正在尝试获取每家酒店的入住率。

SELECT hotel_id, count(room_id)  
FROM  room  
group by room.hotel_id

SELECT h.hotel_id, count(k.room_id) 
FROM room_reservation as kr , room as k , hotel as h
where kr.room_id = k.room_id and k.hotel_id = h.hotel_id 
group by k.hotel_id

我该怎么做？

Answer 1

select aux.hotel_id, ((coalesce(aux2.total, 0)*1.0)/aux.total)*100 as 'ocupancy rate'
from (SELECT hotel_id, count(room_id) as 'total' 
      FROM  room  
      group by room.hotel_id) aux
LEFT OUTER JOIN (SELECT h.hotel_id, COUNT(k.room_id) as 'total'
                 FROM room_reservation as kr
                 INNER JOIN room as k ON (kr.room_id = k.room_id)
                 INNER JOIN hotel as h ON (k.hotel_id = h.hotel_id) 
                 GROUP BY k.hotel_id) aux2 on aux.hotel_id = aux2.hotel_id