LeetCode—行程和用户 LeetCode—行程和用户

SQL架构：

Create table If Not Exists Trips (Id int, Client_Id int, Driver_Id int, City_Id int, Status ENUM('completed', 'cancelled_by_driver', 'cancelled_by_client'), Request_at varchar(50)); Create table If Not Exists Users (Users_Id int, Banned varchar(50), Role ENUM('client', 'driver', 'partner')); Truncate table Trips; insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('1', '1', '10', '1', 'completed', '2013-10-01'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('2', '2', '11', '1', 'cancelled_by_driver', '2013-10-01'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('3', '3', '12', '6', 'completed', '2013-10-01'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('4', '4', '13', '6', 'cancelled_by_client', '2013-10-01'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('5', '1', '10', '1', 'completed', '2013-10-02'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('6', '2', '11', '6', 'completed', '2013-10-02'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('7', '3', '12', '6', 'completed', '2013-10-02'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('8', '2', '12', '12', 'completed', '2013-10-03'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('9', '3', '10', '12', 'completed', '2013-10-03'); insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('10', '4', '13', '12', 'cancelled_by_driver', '2013-10-03'); Truncate table Users; insert into Users (Users_Id, Banned, Role) values ('1', 'No', 'client'); insert into Users (Users_Id, Banned, Role) values ('2', 'Yes', 'client'); insert into Users (Users_Id, Banned, Role) values ('3', 'No', 'client'); insert into Users (Users_Id, Banned, Role) values ('4', 'No', 'client'); insert into Users (Users_Id, Banned, Role) values ('10', 'No', 'driver'); insert into Users (Users_Id, Banned, Role) values ('11', 'No', 'driver'); insert into Users (Users_Id, Banned, Role) values ('12', 'No', 'driver'); insert into Users (Users_Id, Banned, Role) values ('13', 'No', 'driver');

查看表记录：
Trips 表中存所有出租车的行程信息。每段行程有唯一键 Id，Client_Id 和 Driver_Id 是 Users 表中 Users_Id 的外键。Status 是枚举类型，枚举成员为 (‘completed’, ‘cancelled_by_driver’, ‘cancelled_by_client’)。

mysql> select * from trips; +------+-----------+-----------+---------+---------------------+------------+ | Id| Client_Id | Driver_Id | City_Id | Status| Request_at | +------+-----------+-----------+---------+---------------------+------------+ |1 |1 |10 |1 | completed| 2013-10-01 | |2 |2 |11 |1 | cancelled_by_driver | 2013-10-01 | |3 |3 |12 |6 | completed| 2013-10-01 | |4 |4 |13 |6 | cancelled_by_client | 2013-10-01 | |5 |1 |10 |1 | completed| 2013-10-02 | |6 |2 |11 |6 | completed| 2013-10-02 | |7 |3 |12 |6 | completed| 2013-10-02 | |8 |2 |12 |12 | completed| 2013-10-03 | |9 |3 |10 |12 | completed| 2013-10-03 | |10 |4 |13 |12 | cancelled_by_driver | 2013-10-03 | +------+-----------+-----------+---------+---------------------+------------+ 10 rows in set (0.01 sec)

Users 表存所有用户。每个用户有唯一键 Users_Id。Banned 表示这个用户是否被禁止，Role 则是一个表示（‘client’, ‘driver’, ‘partner’）的枚举类型。

mysql> select * from users; +----------+--------+--------+ | Users_Id | Banned | Role| +----------+--------+--------+ |1 | No| client | |2 | Yes| client | |3 | No| client | |4 | No| client | |10 | No| driver | |11 | No| driver | |12 | No| driver | |13 | No| driver | +----------+--------+--------+ 8 rows in set (0.00 sec)

要求：
写一段 SQL 语句查出 2013年10月1日至 2013年10月3日期间非禁止用户的取消率。基于上表，你的 SQL 语句应返回如下结果，取消率（Cancellation Rate）保留两位小数。
【LeetCode—行程和用户】解法：

mysql> select t.Request_at as day, -> round(sum(case when t.status='completed' then 0 else 1 end)/count(*),2) as 'Cancellation Rate' -> from -> Trips t inner join users u1 on t.Client_Id=u1.Users_Id and u1.Banned='No' -> where t.Request_at between '2013-10-01' and '2013-10-03' -> group by t.Request_at; +------------+-------------------+ | day| Cancellation Rate | +------------+-------------------+ | 2013-10-01 |0.33 | | 2013-10-02 |0.00 | | 2013-10-03 |0.50 | +------------+-------------------+ 3 rows in set (0.00 sec)