Question

我正在努力计算MySQL Workbench中另一个计算的总和。我真的不知道如何用文字解释它，所以我会提供一些数据。

这里有表格和数据：

drop database if exists GDPR;
create database if not exists GDPR;

use GDPR;

drop table if exists Company;

create table Company 
(
    id_company int not null auto_increment,
    name varchar (50),
    primary key (id_company)
) auto_increment = 1;

drop table if exists GDPR_steps;

create table GDPR_steps 
(
    id_step int not null auto_increment,
    id_company int,
    name varchar (50),
    primary key (id_step),
    foreign key (id_company) references Company (id_company)
) auto_increment = 1;

drop table if exists compliance;

create table compliance  
(
    id_com int not null auto_increment,
    id_step int,
    initiative varchar (50),
    status varchar (10),
    primary key (id_com),
    foreign key (id_step) references gdpr_steps (id_step)
) auto_increment = 1;

insert into company 
values (null, 'Mango'), (null, 'Kiwi');

insert into gdpr_steps 
values (null, 1, 'Awareness'), (null, 1, 'Information you hold'),
       (null, 2, 'Awareness'), (null, 2, 'Information you hold');

insert into compliance 
values (null, 1, 'E-mail all employees',  '1'),
       (null, 1, 'E-mail all applicants', '0'),
       (null, 2, 'Delete some data', '1'),
       (null, 3, 'Call stakeholders', '1'),
       (null, 4, 'Review data', '0');

我有这个查询，根据属于特定步骤的每个status的{{1}}计算每个公司每个步骤的完成率。

initiatives

上面的查询返回此输出：

select 
    company.name as 'Company',
    gdpr_steps.name as 'ID Step',
    (sum(compliance.status)/count(compliance.status)) * 100 as 'Ratio %'
from
    compliance, company, gdpr_steps
where 
    gdpr_steps.id_step = compliance.id_step 
    and company.id_company = gdpr_steps.id_company
group by 
    compliance.id_step, company.id_company;

现在，当我想计算每家公司的比例时（例如，将步骤1与步骤2中的比率相加并将其除以2），我无法使其发挥作用。这就像

Company   ID Step               Ratio %
-----------------------------------------
Mango     Awareness             50
Mango     Information you hold  100
Kiwi      Awareness             100
Kiwi      Information you hold  0

在我们的案例中会产生类似的结果：

Company   Overall ratio %
Mango     (Awareness (50) + Information you hold (100)) / nr of steps (2 in our case)
Kiwi      (Awareness  (0) + Information you hold (100)) / nr of steps (2 in our case)

我尝试了类似

的内容

Name    Overall ratio %
Mango   75
Kiwi    50

这个似乎根本不起作用，因为我收到的值与预期完全不同。

你能解释一下我的错误吗？

亲切的问候！

Answer 1

看起来你好像是在以下......

SELECT company
     , AVG(`ratio %`) n
  FROM
     (
        -- your query here --
     ) x
 GROUP
    BY company;

MySQL计算错误总和

1 个答案: