para simular
FULL JOIN
no mysql, você precisa UNION
o resultado de Right Join e Left Join de ambas as tabelas SELECT Persons.Name, Persons.P_Id, Invoice.Id
FROM Persons
LEFT JOIN Invoice
ON Persons.P_Id=Invoice.P_Id
UNION
SELECT Persons.Name, Persons.P_Id, Invoice.Id
FROM Invoice
LEFT JOIN Persons
ON Persons.P_Id=Invoice.P_Id