Nelze zpracovat dotaz MySQL FULL JOIN

za účelem simulace FULL JOIN v mysql potřebujete UNION výsledek Right Join a Left Join z obou stolů

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

• Ukázka SQLFiddle