string reqSql = "select c_id,c_nom,c_cat1,sum(tot_bas_fb) as tot_ca from CLI left join PIEDS_V on cli.c_id=pieds_v.id_cli where ... group by c_id,c_nom,c_cat1 \r\n"
              + "select f_id,f_nom,f_cat2,sum(tot_bas_fb) as tot_ca from FOU left join PIEDS_A on fou.f_id=pieds_a.id_fou where ... group by f_id,f_nom,f_cat2";
DataSet ds = Api.Zselect(MercatorController.Globals.RepData, reqSql);
if (ds != null)
{
    List<CliAndCa> listCliAndCa = ds.Tables[0].RowsEnumerable<CliAndCa>().ToList();
    List<FouAndCa> listFouAndCa = ds.Tables[1].RowsEnumerable<FouAndCa>(dr => dr["f_id"].ToString().StartsWith("A")).ToList();
}