We must use the ON clause to join three tables. code example

Example: 3 joins in sql

SELECT e.FIRST_NAME ,     -- coming from EMPLOYEES table
			 d.DEPARTMENT_NAME ,-- coming from DEPARTMENTS table
			 l.CITY ,           -- coming from LOCATIONS table
			 c.COUNTRY_NAME ,   -- coming from COUNTRIES table
			 r.REGION_NAME      -- coming from REGIONS table
FROM EMPLOYEES e 
	INNER JOIN DEPARTMENTS d on e.DEPARTMENT_ID = d.DEPARTMENT_ID
	INNER JOIN LOCATIONS l   on l.LOCATION_ID   = d.LOCATION_ID
	INNER JOIN COUNTRIES c   on l.COUNTRY_ID    = c.COUNTRY_ID
	INNER JOIN REGIONS r     on c.REGION_ID     = r.REGION_ID ;