SQL查询可预订的房间

我一直在尝试创建一个查询来检查两个日期之间的可用房间，但迄今为止没有成功。请查找用于创建下表的sql代码。我真的需要你的帮助。这样做是因为系统希望我添加更多细节

CREATE TABLE rooms (
    id   NUMERIC(3) NOT NULL,
    type VARCHAR2(11) NOT NULL,
    CONSTRAINT pk_rooms PRIMARY KEY (id),
    CONSTRAINT fk_type
    );

INSERT INTO rooms VALUES (101, 'Excellent');
INSERT INTO rooms VALUES (102, 'Excellent');
INSERT INTO rooms VALUES (103, 'Excellent');
INSERT INTO rooms VALUES (104, 'Excellent');
INSERT INTO rooms VALUES (105, 'Excellent');
INSERT INTO rooms VALUES (106, 'Excellent');
INSERT INTO rooms VALUES (107, 'Excellent');
INSERT INTO rooms VALUES (108, 'Excellent');
INSERT INTO rooms VALUES (109, 'Excellent');
INSERT INTO rooms VALUES (110, 'Excellent');
INSERT INTO rooms VALUES (111, 'Excellent');
INSERT INTO rooms VALUES (112, 'Excellent');

CREATE TABLE bookings_roombookings (
book_id  VARCHAR(20) NOT NULL, 
room_id  NUMBER NOT NULL,  
fromdate DATE NOT NULL, 
todate   DATE NOT NULL, 
guest1   VARCHAR(40) NOT NULL, 
guest2   VARCHAR(40), 
guest3   VARCHAR(40), 
CONSTRAINT cpk PRIMARY KEY (book_id, room_id),  
CONSTRAINT fk_rid FOREIGN KEY (room_id) REFERENCES rooms(id));

INSERT INTO bookings_roombookings VALUES ( 
'DTR5000000', 320, 
'01-JUN-2020', '01-SEP-2020', 
'D.Trump', 'H.Clinton', 'S.Daniels');

INSERT INTO bookings_roombookings VALUES ( 
'DRI0000002', 102, 
'11-DEC-19', '01-SEP-20', 
'D.Ridley', NULL, NULL);

我的质询如下：

select r.id from rooms r
where  r.id not in
       ( select bkr.room_id from bookings_roombookings bkr
         where  (fromdate > '15-JUN-20') and (todate < '18-JUN-20') );

但这将返回bkr表的两行。非常感谢您的帮助。

您可以从room表开始，使用not exists条件和相关子查询来删除预订期与目标日期范围重叠的房间：

select r.* 
from rooms r 
where not exists (
    select 1
    from bookings_roombookings bkr
    where 
        bkr.room_id = r.id
        and bkr.fromdate <= date'2020-06-15'
        and bkr.todate >= date'2020-06-18'
)

---

注意：不要像fromdate>'15-JUN-20'中那样依赖从字符串到日期的隐式转换，这取决于数据库和会话的nls设置；相反，您可以使用date LITERALS，它是ANSI SQL标准的一部分，Oracle支持它，如date'yyyy-mm-dd'。

不要将日期存储为varchar。将其存储为Date您在bookings\u roombookings中插入320，但它在rooms表中不存在。是的，数据比我最初插入的要多