Marc Zaharescu Marc Zaharescu - 7 months ago 6
SQL Question

SQL: Combine two queries into a single one

I have the following two queries:

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;


And I was trying to combine them together into a single one as following:

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;


But it doesn't seem to work. Could anybody point out what I am doing wrong? Any help is much appreciated.

EDIT: To make it clear the first query displays the number of project related to each industry. The second query displays the number of consultants related to each industry.

I want the third query to display the information from the first two queries in the same table on 3 separate columns: Industry Name, #Projects, #Consultants

The table structures is as following, where -> describes the primary and foreign keys of the tables:

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

You were almost there.As per my understanding below query should work for you .

QUERY

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