หาฟิลด์ที่จะเชื่อมกัน(FK) https://www.thaicreate.com/php/forum/037157.html
ดูที่พี่วินนะครับ
select tb1.*,tb2.*,tb3.*
from tb1,tb2,tb3
where 1
and tb1.id=tb2.id
and tb2.id=tb3.id
and tb3.id='value'
SELECT Employee.emFirstname,Employee.emLastname,Employee.tel,Employee.email,
Company.companyName,
Office.officeName,Office.salary
FROM Employee JOIN Company
ON Employee.companyID = Company.companyID
JOIN Office
ON Employee.officeID = Office.officeID