Я хочу выбрать группу счетчиков приращений в поле medec, пожалуйста, как это сделать, и я хотел бы, чтобы результат был таким, как показано ниже 
SELECT @n := @n + 1 as n, Nb, medec, prest, Nompatient, ftt, Categorie
FROM (SELECT @n := 0, m.nom as medec, s.id as Nb, ft.id as ftt, sv.libelle , m.nom , pr.libelle as prest, p.nom as Nompatient, ct.libelle as Categorie from services sv, medecins m, sejours s, sejourprestations sjp, prestations pr, patients p, categoriepatients ct, factures ft
WHERE sv.id = s.service_id
AND s.medecin_id = m.id
AND s.patient_id = p.id
AND s.categorie_patient_id = ct.id
AND sjp.sejour_id = s.id
AND sjp.prestation_id = pr.id
AND s.facture_id=ft.id
AND day(s.created_at) = day(CURRENT_DATE)) AS ishmael
GROUP BY n
ORDER BY medec