Ah pero hombre................se me está pegando tu SQL...je, je. ya lo he resuelto...
Código PHP:
SELECT P.provider_id, P.company_name, P.country, P.medical_speciality, P.sales_manager, C.status_2, C.provider_call_log_id
FROM provider P inner join provider_call_log C on P.Provider_id=C.Provider_Id
WHERE P.active='prospect' AND P.sales_manager='Pedro Perez' AND
C.provider_call_log_id = (SELECT Max(provider_call_log_id) from provider_call_log
where provider_id=P.Provider_Id) UNION SELECT P.provider_id, P.company_name, P.country, P.medical_speciality, P.sales_manager, NULL AS status_2, NULL as provider_call_log_id from provider P WHERE P.active='prospect' AND P.sales_manager='Pedro Perez' AND Provider_id not in (SELECT Distinct(Provider_id) from Provider_call_Log)