大数据第40天—Mysql练习题11-行程和用户-杨大伟

需求：写一段 SQL 语句查出 2019年10月1日 至 2019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。

取消率的计算方式如下：(被司机或乘客取消的非禁止用户生成的订单数量) / (非禁止用户生成的订单总数)

Trips表：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’)。

 

Id	Client_Id	Driver_Id	City_Id	Status	Request_at
1	1	10	1	completed	2019-10-01
2	2	11	1	cancelled_by_driver	2019-10-01
3	3	12	6	completed	2019-10-01
4	4	13	6	cancelled_by_client	2019-10-01
5	1	10	1	completed	2019-10-02
6	2	11	6	completed	2019-10-02
7	3	12	6	completed	2019-10-02
8	2	12	12	completed	2019-10-03
9	3	10	12	completed	2019-10-03
10	4	13	12	cancelled_by_driver	2019-10-03

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。

Users_Id	Banned	Cancellation Rate
1	No	client
2	Yes	client
3	No	client
4	No	client
10	No	driver
11	No	driver
12	No	driver
13	No	driver

展示效果：

Day	Cancellation Rate
2019-10-01	0.33
2019-10-02	0.00
2019-10-03	0.50

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'));

insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (1, 1, 10, 1, 'completed', '2019-10-01');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (2, 2, 11, 1, 'cancelled_by_driver', '2019-10-01');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (3, 3, 12, 6, 'completed', '2019-10-01');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (4, 4, 13, 6, 'cancelled_by_client', '2019-10-01');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (5, 1, 10, 1, 'completed', '2019-10-02');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (6, 2, 11, 6, 'completed', '2019-10-02');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (7, 3, 12, 6, 'completed', '2019-10-02');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (8, 2, 12, 12, 'completed', '2019-10-03');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (9, 3, 10, 12, 'completed', '2019-10-03');
insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values (10, 4, 13, 12, 'cancelled_by_driver', '2019-10-03');

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');

最终SQL:

方法一：
SELECT 
      T.request_at AS `Day`, 
      ROUND(
            SUM(IF(T.STATUS = 'completed',0,1))/ COUNT(T.STATUS),
            2
            ) AS `Cancellation Rate`
FROM 
      Trips AS T
JOIN 
      Users AS U1 
ON 
      T.client_id = U1.users_id AND U1.banned ='No'
JOIN 
      Users AS U2 
ON 
      T.driver_id = U2.users_id AND U2.banned ='No'
WHERE 
      T.request_at BETWEEN '2019-10-01' AND '2019-10-03'
GROUP BY 
      T.request_at;

方法二：
SELECT 
      T.request_at AS `Day`, 
      ROUND(
            SUM(IF(T.STATUS = 'completed',0,1))/ COUNT(T.STATUS),
            2
            ) AS `Cancellation Rate`
FROM 
     trips AS T 
LEFT JOIN (
            SELECT
                  users_id
            FROM
                  users
            WHERE  
                  banned = 'Yes'
           ) AS A 
ON 
     T.Client_Id = A.users_id
LEFT JOIN (
            SELECT
                  users_id
            FROM 
                  users
            WHERE 
                  banned = 'Yes'
           ) AS A1
ON 
     T.Driver_Id = A1.users_id
WHERE 
     A.users_id IS NULL 
     AND A1.users_id IS NULL 
     AND T.request_at BETWEEN '2019-10-01' AND '2019-10-03'
GROUP BY 
     T.request_at;

方法三：
SELECT 
     T.request_at AS `Day`, 
     ROUND(
           SUM(IF(T.STATUS = 'completed',0,1))/ COUNT(T.STATUS),
           2
           ) AS `Cancellation Rate`
FROM
     trips AS T
WHERE 
     T.Client_Id NOT IN (
                          SELECT 
                                 users_id
                          FROM 
                                 users
                          WHERE 
                                 banned = 'Yes'
     )
AND
     T.Driver_Id NOT IN (
                           SELECT 
                                 users_id
                           FROM  
                                 users
                           WHERE 
                                 banned = 'Yes'
     )
AND 
     T.request_at BETWEEN '2019-10-01' AND '2019-10-03';