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➤微信公众号：山青咏芝（shanqingyongzhi）
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SQL架构
1 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)) 2 Create table If Not Exists Users (Users_Id int, Banned varchar(50), Role ENUM('client', 'driver', 'partner')) 3 Truncate table Trips 4 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('1', '1', '10', '1', 'completed', '2013-10-01') 5 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('2', '2', '11', '1', 'cancelled_by_driver', '2013-10-01') 6 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('3', '3', '12', '6', 'completed', '2013-10-01') 7 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('4', '4', '13', '6', 'cancelled_by_client', '2013-10-01') 8 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('5', '1', '10', '1', 'completed', '2013-10-02') 9 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('6', '2', '11', '6', 'completed', '2013-10-02') 10 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('7', '3', '12', '6', 'completed', '2013-10-02') 11 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('8', '2', '12', '12', 'completed', '2013-10-03') 12 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('9', '3', '10', '12', 'completed', '2013-10-03') 13 insert into Trips (Id, Client_Id, Driver_Id, City_Id, Status, Request_at) values ('10', '4', '13', '12', 'cancelled_by_driver', '2013-10-03') 14 Truncate table Users 15 insert into Users (Users_Id, Banned, Role) values ('1', 'No', 'client') 16 insert into Users (Users_Id, Banned, Role) values ('2', 'Yes', 'client') 17 insert into Users (Users_Id, Banned, Role) values ('3', 'No', 'client') 18 insert into Users (Users_Id, Banned, Role) values ('4', 'No', 'client') 19 insert into Users (Users_Id, Banned, Role) values ('10', 'No', 'driver') 20 insert into Users (Users_Id, Banned, Role) values ('11', 'No', 'driver') 21 insert into Users (Users_Id, Banned, Role) values ('12', 'No', 'driver') 22 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’).
+----+-----------+-----------+---------+--------------------+----------+ | 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_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 between Oct 1, 2013 and Oct 3, 2013. For the above tables, your SQL query should return the following rows with the cancellation rate being rounded to two decimal places.
+------------+-------------------+ | Day | Cancellation Rate | +------------+-------------------+ | 2013-10-01 | 0.33 | | 2013-10-02 | 0.00 | | 2013-10-03 | 0.50 | +------------+-------------------+
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| +----+-----------+-----------+---------+--------------------+----------+
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 | +----------+--------+--------+
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。
+------------+-------------------+ | Day | Cancellation Rate | +------------+-------------------+ | 2013-10-01 | 0.33 | | 2013-10-02 | 0.00 | | 2013-10-03 | 0.50 | +------------+-------------------+
158ms
1 # Write your MySQL query statement below 2 select request_at Day, round(sum(if(t.Status like 'cancelled%',1,0))/ count(t.Status),2) as 'Cancellation Rate' 3 from trips t 4 join users u 5 on t.client_id = u.users_id 6 and u.banned = 'No' 7 where request_at BETWEEN '2013-10-01' AND '2013-10-03' 8 group by request_at;
160ms
1 select 2 R1.Request_at as `Day`, 3 round(sum(case when R1.Status !='completed' -- in ('cancelled_by_driver','cancelled_by_client') 4 then 1 5 else 0 6 end)/count(1),2) 7 as `Cancellation Rate` 8 from 9 Trips R1 10 left join Users R2 on R1.Client_Id = R2.Users_Id 11 left join Users R3 on R1.Driver_Id = R3.Users_Id 12 where 13 R1.Request_at between '2013-10-01' and '2013-10-03' 14 and R2.Banned = 'No' 15 and R3.Banned = 'No' 16 group by R1.Request_at 17 order by R1.Request_at
162ms
1 # Write your MySQL query statement below 2 select 3 a.request_at as Day, 4 round(sum(case when status like 'cancelled_by_%'then 1 else 0 end)/count(id),2) as 'Cancellation Rate' 5 from 6 trips a 7 left join 8 users b 9 on a.client_id=b.users_id 10 where b.role='client' and b.banned='No' and a.request_at between '2013-10-01' and '2013-10-03' 11 group by 1 12 order by 1
164ms
1 # Write your MySQL query statement below 2 SELECT T.Request_at as Day, ROUND(SUM(IF(T.Status like "cancelled%", 1, 0))/COUNT(T.Status), 2) as "Cancellation Rate" 3 From Trips as T 4 WHERE (T.Client_Id IN (SELECT Users_Id as aUsers From Users WHERE (Banned like "No") AND (Role like "client"))) 5 AND (T.Driver_Id IN (SELECT Users_Id as aDrivers From Users WHERE (Banned like "No") AND (Role like "driver"))) 6 AND (Request_at BETWEEN "2013-10-01" AND "2013-10-03") 7 GROUP BY Day