选择每隔一天选择公交车行程方向

Question

我正在开发一个公交车车票预订系统。在这里，我已经为所有路线制作了表格，并在表格中添加了bus_number、fields等字段。现在我们的公交车每隔一天反向行驶，也就是说，如果一辆公交车在2011年12月21日从X->Y行驶，那么下一天同一辆公交车将行驶Y->X。那么，如何获得公交车的方向呢？如果我为每个公交车服务提供商制作了表格，并添加公交车号码并添加一个标识符，比如' to‘作为日期，我想就有可能知道所有未来几天的状态。我不知道这是不是一个好主意，所以请帮助我。

Answer 1

如果不知道现有表的确切细节，就很难提供一个明确的解决方案。无论如何，这里有一个建议，告诉你如何保持公交车的停靠点和票价：

CREATE TABLE `bus` (
  `id` int unsigned not null primary key auto_increment,
  `bus_number` varchar(55) not null,
   UNIQUE KEY `busUidx1` (`bus_number`)
) ENGINE=InnoDB;

CREATE TABLE `bus_stop` (
  `id` int unsigned not null primary key auto_increment,
  `stop_description` varchar(250) not null,
  UNIQUE KEY `bus_stopUidx1` (`stop_description`)
) ENGINE=InnoDB;

CREATE TABLE `bus_route` (
  `id` int unsigned not null primary key auto_increment,
  `bus_id` int unsigned not null,
  `route_date` date not null,
  `bus_start_stop_id` int unsigned not null,
  `bus_end_stop_id` int unsigned not null,
  `fare` decimal (10,2) not null,
   UNIQUE KEY `bus_stopUidx1` (`bus_id`,`route_date`),
CONSTRAINT `fk_bus_route_bus_fk1` FOREIGN KEY (`bus_id`) REFERENCES `bus` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_bus_route_stop_fk1` FOREIGN KEY (`bus_start_stop_id`) REFERENCES `bus_stop` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_bus_route_stop_fk2` FOREIGN KEY (`bus_end_stop_id`) REFERENCES `bus_stop` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB;

使用此模型，您应该能够存储公交车列表(在bus表中)、所有可能的站点列表(在bus_stop表中)和给定日期的公交车路线。它还将允许您灵活地打破“公交车从X>Y旅行，然后总是从Y>X返回”的规则，如果我过去乘坐的公交车是任何有用的东西，可能会被证明是有用的;-)

编辑

因此，这里有一些示例数据来尝试进一步说明我的答案：

insert into bus (bus_number) values ('Red Bus 1');
insert into bus (bus_number) values ('Red Bus 2');
insert into bus (bus_number) values ('Yellow Bus 1');
insert into bus (bus_number) values ('Yellow Bus 2');

insert into bus_stop (stop_description) values ('Stop 1');
insert into bus_stop (stop_description) values ('Stop 2');
insert into bus_stop (stop_description) values ('Stop 3');
insert into bus_stop (stop_description) values ('Stop 4');

insert into bus_route (bus_id,route_date,bus_start_stop_id,bus_end_stop_id,fare)
values (
(select id from bus where bus_number = 'Red Bus 1'),
'2011-12-11',
(select id from bus_stop where stop_description = 'Stop 1'),
(select id from bus_stop where stop_description = 'Stop 2'),
3.45);

insert into bus_route (bus_id,route_date,bus_start_stop_id,bus_end_stop_id,fare)
values (
(select id from bus where bus_number = 'Red Bus 1'),
'2011-12-12',
(select id from bus_stop where stop_description = 'Stop 2'),
(select id from bus_stop where stop_description = 'Stop 1'),
3.45);

insert into bus_route (bus_id,route_date,bus_start_stop_id,bus_end_stop_id,fare)
values (
(select id from bus where bus_number = 'Yellow Bus 1'),
'2011-12-11',
(select id from bus_stop where stop_description = 'Stop 3'),
(select id from bus_stop where stop_description = 'Stop 4'),
1.95);

insert into bus_route (bus_id,route_date,bus_start_stop_id,bus_end_stop_id,fare)
values (
(select id from bus where bus_number = 'Yellow Bus 1'),
'2011-12-12',
(select id from bus_stop where stop_description = 'Stop 4'),
(select id from bus_stop where stop_description = 'Stop 3'),
1.95);

最后是一个将表连接在一起的查询：

select b.bus_number,
       br.route_date,
       bs.stop_description as start,
       be.stop_description as end,
       br.fare
from bus_route br
inner join bus b on b.id = br.bus_id
inner join bus_stop bs on bs.id = br.bus_start_stop_id
inner join bus_stop be on be.id = br.bus_end_stop_id;