SELECT
 (T_SAL.MatriculeSalarie + ' ' + isnull(T_SAL.Nom, '') + ' '  + isnull(T_SAL.Prenom, '') ) as Clo1,
 'Dernière visite médicale : '+  Isnull((CONVERT(VARCHAR(13),T_HST_MEDECINE.DateVisite, 113)), 'vide') as Col2
FROM
  T_PAI,
  T_SAL
  LEFT OUTER JOIN T_HST_MEDECINE ON T_HST_MEDECINE.NumSalarie=T_SAL.SA_CompteurNumero
                  AND T_HST_MEDECINE.InfoEnCours=1
Where   (T_HST_MEDECINE.DateVisite is null)
    OR  (    DATEPART(mm, DATEADD(mm, ISNULL(%visitesMedicales%,0), T_HST_MEDECINE.DateVisite)) = T_PAI.MoisEnCours
         and DATEPART(yyyy, DATEADD(mm, ISNULL(%visitesMedicales%,0), T_HST_MEDECINE.DateVisite)) = T_PAI.AnneeEnCours)

Order by T_SAL.MatriculeSalarie