Ajá...
Código PHP:
select i.provider_name, i.patient, i.payment_type,
DATE_FORMAT(i.date,'%m/%d/%Y') as date, i.provider_invoice, i.insurer,
i.amount_paid, i.md_fees, i.total, i.created_date, i.created_by, p.business_address, p.city, p.country, p.phone_number
from invoice i, providers p WHERE i.id ='5' AND p.company_name = (SELECT provider_name from invoice
where id ='5'