[英]SQL: Combine two queries into a single one
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。 有人能指出我做错了什么吗? 非常感谢任何帮助。
编辑:为了清楚起见,第一个查询显示了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 3 个单独列的同一个表中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
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
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