SQL

Posted 2021-06-15 yuexiuping

8.行程和用户

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	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

展示效果：

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

建表语句：

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\', \'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\');
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\');

方法1：

select 
	t.request_at as \'Day\',
	Round(sum(if(t.status = \'complete\',0,1))/count(t.status))
from
	Trips as t
join 
	Users as u
on
	t.cilent_id = u.user.id 
and 
	u.Banned = \'No\'
where 
	t.request_at between \'2019-10-01\' AND \'2019-10-03\'
group by
	t.request_at;