Inner join between three tables in mysql

问题

I have 3 tables called

• Companies
• Contacts
• Campaigns

Contacts has foreign key of companies. Companies has foreign key of campaigns. All of them have a column 'name'. I need a join table which will have contact name company name and campaign name.

contact
id   name company_id
companies
id   name campaign_id
campaigns
id   name company_id

回答1:

select con.name as contact_name , com.name as company_name,campa.name as campaign_name
from contact con inner join company com
on con.companyid = com.companyid
inner join campaign campa
on com.campaignid = campa.campaignid

assuming id columns of respected tables

回答2:

SELECT contacts.name,companies.name,campaigns.name 
FROM contacts 
INNER JOIN 
(companies INNER JOIN campaigns 
ON campaigns.campaignid=companies.campaignid) 
ON contacts.companyid=companies.companyid
AND //add any additional filters HERE

hope this was helpful

来源：https://stackoverflow.com/questions/9293122/inner-join-between-three-tables-in-mysql