Update and rename 0262. Trips and Users.sql to 0262.(Hard) Trips and …

…Users.sql

Database/0262.(Hard) Trips and Users.sql

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+/****************************************************************************************************
+262. Trips and Users
+262. 行程和用户
+
+Difficulty: Hard
+
+SQL Schema:
+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')
+
+The Trips table holds all taxi trips. 
+Each trip has a unique Id, while Client_Id and Driver_Id are both foreign keys to the Users_Id at the Users table. 
+Status is an ENUM type of (‘completed’, ‘cancelled_by_driver’, ‘cancelled_by_client’).
+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’)。
+
++----+-----------+-----------+---------+--------------------+----------+
+| 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|
++----+-----------+-----------+---------+--------------------+----------+
+
+The Users table holds all users. 
+Each user has an unique Users_Id, and Role is an ENUM type of (‘client’, ‘driver’, ‘partner’).
+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 |  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 |
++----------+--------+--------+
+
+Write a SQL query to find the cancellation rate of requests made by unbanned users 
+(both client and driver must be unbanned) between Oct 1, 2013 and Oct 3, 2013. 
+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。
+
+The cancellation rate is computed by 
+dividing the number of canceled (by client or driver) requests made by unbanned users 
+by the total number of requests made by unbanned users.
+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)
+
+For the above tables, your SQL query should return the following rows with the cancellation rate being rounded to two decimal places.
+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。
+
++------------+-------------------+
+|     Day    | Cancellation Rate |
++------------+-------------------+
+| 2013-10-01 |       0.33        |
+| 2013-10-02 |       0.00        |
+| 2013-10-03 |       0.50        |
++------------+-------------------+
+****************************************************************************************************/
+
+
+--Method1:
+SELECT Request_at AS Day,
+       ROUND(SUM(CancelCount) / SUM(TotalCount), 2) AS [Cancellation Rate]
+FROM (
+    SELECT Client_Id,
+           Request_at, 
+           CASE WHEN Status IN ('cancelled_by_driver', 'cancelled_by_client') THEN 1.0 ELSE 0.0 END AS CancelCount,
+           CASE WHEN Status = Status THEN 1.0 ELSE 0.0 END AS TotalCount
+    FROM Trips AS t
+    INNER JOIN Users AS u
+    ON t.Client_Id = u.Users_Id
+    WHERE Banned = 'No'
+    AND CAST(Request_at AS DATE) BETWEEN '2013-10-01' AND '2013-10-03'
+) AS t
+GROUP BY Request_at
+ORDER BY Day
+
+
+/****************************************************************************************************/
+
+
+--Method2:
+SELECT t.Request_at AS Day,
+	ROUND (CAST(SUM(CASE WHEN t.Status = 'completed' THEN 0 ELSE 1 END) AS float) / COUNT(t.Status), 2) AS 'Cancellation Rate' 
+FROM Trips t
+	LEFT JOIN Users u1 ON t.Client_ID = u1.Users_Id
+	LEFT JOIN Users u2 ON t.Driver_ID = u2.Users_Id
+WHERE Request_at BETWEEN '2013-10-01' AND '2013-10-03' 
+	AND u1.Banned = 'No'
+	AND u2.Banned = 'No'
+GROUP BY t.Request_at
+
+