Question

表如下

rooms(RoomId(PK)(int),
      RoomName(varchar))

bookings(RoomId(FK)(int),
         From_D(date),
         To_D(date),
         Bookee(varchar))

(PK-primary Key ,FK-foreign Key)

给出arrival(From_D)和departure(To_D)的日期，我如何找出可用房间的ID

我尝试过：

SELECT DISTINCT RoomId 
FROM bookings 
WHERE  arrival not in(From_D,To_d) AND 
       departure not in(From_D,To_d)

但是，如果在数据库中存储了多个预订房间，就会看到我的数据库问题的结构，即使房间在那个日期范围内不是免费的，它也会预订房间

Answer 1

请考虑以下图表（对不起笔迹的影响）：

在上图中，我们可以在水平轴上看到日期范围。 From_D至To_D代表特定房间的预订空位。考虑到四种情况的到达和离开日期（分别以A _i和D _i表示）。

当到达和离开日期完全在预订的位子的左侧或右侧时，我们可以清楚地看到特定房间仅可用。

我们可以在GROUP BY上RoomID，并使用HAVING子句仅考虑那些预订符合上述标准的房间。

查询将仅是以下内容：

SELECT RoomID 
FROM bookings 
GROUP BY RoomID 
HAVING 
  SUM((From_D < :arrival AND To_D < :arrival) 
             OR 
      (From_D > :departure AND To_D > :departure)) = COUNT(*)

Demo on DB Fiddle

CREATE TABLE `rooms` (
 `RoomId` int(4) NOT NULL,
 `RoomName` varchar(20) DEFAULT NULL,
 PRIMARY KEY (`RoomId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `bookings` (
 `RoomId` int(4) NOT NULL,
 `From_D` date NOT NULL,
 `To_d` date NOT NULL,
 `B_Name` varchar(20) NOT NULL,
 KEY `RoomId` (`RoomId`),
 CONSTRAINT `bookings_ibfk_1` FOREIGN KEY (`RoomId`) REFERENCES `rooms` (`RoomId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `rooms` (`RoomId`, `RoomName`) VALUES 
('1', 'Auditorium'), 
('2', 'Room2'), 
('3', 'Room3'), 
('4', 'Room4'), 
('5', 'Room5');

INSERT INTO `bookings` (`RoomId`, `From_D`, `To_d`, `B_Name`) VALUES 
('1', '2018-11-01', '2018-11-03', 'Trance'), 
('2', '2018-11-02', '2018-11-07', 'Alcoding'), 
('3', '2018-11-01', '2018-11-04', 'DebSoc'), 
('4', '2018-11-12', '2018-11-17', 'MunSoc'), 
('5', '2018-11-03', '2018-11-06', 'Pulse');

查询：检查2018年11月1日至2018年11月3日之间是否有空

SELECT RoomId 
FROM bookings 
GROUP BY RoomID 
HAVING 
  SUM((From_D < '2018-11-01' AND To_D < '2018-11-01') 
             OR 
      (From_D > '2018-11-03' AND To_D > '2018-11-03')) = COUNT(*)

结果：根据样本数据，只有RoomId 4可用

| RoomId |
| ------ |
| 4      |

Answer 2

在您的日期上使用 BETWEEN 和 AND

SELECT DISTINCT RoomId FROM bookings    
WHERE (date_field BETWEEN From_D AND To_d)

Answer 3

select distinct r.*
from rooms r
    left join bookings b on b.RoomId=r.RoomId
where b.RoomId is null or @arrival > To_D or @departure < from_td

Answer 4

Try this :
    SELECT * FROM   rooms room1
    WHERE  NOT EXISTS (SELECT *
                FROM   booking booking1
                       WHERE  room1.roomid = booking1.roomid AND
                              (:from_d BETWEEN booking1.from_d AND booking1.to_d OR
                               :to_d   BETWEEN booking1.from_d AND booking1.to_d))

MySql查询查找给定日期“从”和“到”的可用房间

4 个答案: