Question

SELECT HOTEL.ROOM
FROM HOTEL
  LEFT OUTER JOIN BOOKED
 ON BOOKED.ROOM = HOTEL.ROOM

 WHERE
    TO_DATE('&STARTDATE','DD-MM-YY') BETWEEN BOOKED.ARRIVALDATE 
 AND BOOKED.ARRIVALDATE + &NIGHTS

我需要帮助，我需要搜索预订的房间并返回可用的房间。基本上用户在查询中输入日期，以及他住的晚数。这是在BOOKED表中查找的，如果日期等于那意味着房间被预订，它不应该从HOTEL.ROOM表中选择那个。编辑：将RIGHT OUTER JOIN改为LEFT OUTER JOIN，只是意识到它是从错误的表中选择数据

Answer 1

您日期范围内的预订：

SELECT *
FROM   BOOKED
WHERE  TO_DATE('&STARTDATE','DD-MM-YY') BETWEEN ARRIVALDATE AND ARRIVALDATE + &NIGHTS

扩展以查找此列表中的HOTEL个房间，即已预订：

SELECT ROOM
FROM   HOTEL
WHERE  EXISTS (
         SELECT *
         FROM   BOOKED
         WHERE  TO_DATE('&STARTDATE','DD-MM-YY') BETWEEN ARRIVALDATE AND ARRIVALDATE + &NIGHTS
         AND    ROOM = HOTEL.ROOM
       )

那些不在此列表中的人，即没有预订：

SELECT ROOM
FROM   HOTEL
WHERE  NOT EXISTS (
         SELECT *
         FROM   BOOKED
         WHERE  TO_DATE('&STARTDATE','DD-MM-YY') BETWEEN ARRIVALDATE AND ARRIVALDATE + &NIGHTS
         AND    ROOM = HOTEL.ROOM
       )

SQL，选择与您找到的实体不相等的实体

1 个答案: