select UNIQUE a.tipo,a.num_oc,a.fech_oc,b.nom_sp,a.c_flete,a.otros_g 
  FROM cotb00014 a,cotb00001 b,cotb00015 d 
  WHERE b.cod_sp = a.cod_sp AND b.cod_sp_sec = a.cod_sp_sec AND 
        a.num_oc = d.num_oc AND a.tipo = d.tipo AND 
        a.fech_oc between "010197" AND "110897" AND 
        a.status_t is null ORDER BY 1,2