SQL：将两个查询合并为一个

Question

我有以下两个查询：

    Select count(project.id) as num_project , 
           industry.name as industry_name 
    from   project, project_industry, industry 
    where  industry.id= project_industry.industry_id and 
           project.id = project_industry.project_id  
    group by industry.id;

Select count(user.id) as num_consultants , 
       industry.name as industry_name 
from   consultant_profile, industry_experience,user, industry 
where  industry_experience.consultant_profile_id = consultant_profile.id
       and industry_experience.industry_id= industry.id 
       and user.type=0 
       and user.is_active=1 
       and consultant_profile.user_id=user.id 
group by industry_id;

我试图将它们组合成一个，如下所示：

SELECT i.name AS industry_name, num_projects, num_consultants
FROM   industry i
JOIN   (SELECT   pc.industry_id, COUNT(p.id) AS num_projects
        FROM     project p
        JOIN     project_industry pc ON p.id = pc.project_id
        GROUP BY pc.industry_id) x ON x.industry_id = i.id
JOIN   (SELECT   y.industry_id, COUNT(u.id) AS num_consultants
        FROM     user u, consultant_profile cp
        JOIN     project_experience pe on pe.consultant_profile_id = cp.id
        WHERE    u.is_active = 1 AND u.type = 0
        GROUP BY y.industry_id) z ON z.industry_id = i.id;

但它似乎不起作用。谁能指出我做错了什么？非常感谢任何帮助。

编辑：为了清楚起见，第一个查询显示与每个行业相关的项目数量。第二个查询显示与每个行业相关的顾问数量。

我希望第三个查询在同一个表的 3 个单独列上显示前两个查询的信息：行业名称、#Projects、#Consultants

表结构如下，其中 -> 描述了表的主键和外键：

Project -> project.id
Project_industry -> project_industry.id, project_id, industry_id
Industry -> industry.id

user -> user.id
Consultant_profile -> consultant_profile.id, user_id
Industry_Experience -> industry_experience.id, consultant_profile_id, industry_id
Industry -> industry.id

Answer 1

你快到了。根据我的理解，下面的查询应该适合你。

查询

SELECT 
    T1.industry_name ,
    num_project ,
    num_consultants  
FROM 
    ( 
        SELECT 
            COUNT(project.id) AS num_project, 
            industry.name AS industry_name,
            industry.id AS id  
        FROM 
            project, 
            project_industry, 
            industry 
        WHERE 
            industry.id = project_industry.industry_id AND 
            project.id = project_industry.project_id  
        GROUP BY industry.id 
    ) T1 
    JOIN 
        ( 
            SELECT 
                COUNT(user.id) AS num_consultants, 
                industry.name AS industry_name,
                industry.id AS id 
            FROM 
                consultant_profile, 
                industry_experience,
                user, 
                industry 
            WHERE 
                industry_experience.consultant_profile_id = consultant_profile.id AND 
                industry_experience.industry_id = industry.id AND 
                user.type = 0 AND 
                user.is_active = 1 AND 
                consultant_profile.user_id = user.id 
            GROUP BY 
                industry_id 
        ) T2 ON T1.id = T2.id