jQuery("#navgrid").jqGrid({
       url:'abilita.php?q=1',
    datatype: "xml",
       colNames:['Partita Iva','Ragione Sociale', 'Utente','Indirizzo','Città','Cap','Provincia','Telefono','Email','Attivo','Cancellato'],
       colModel:[
           {name:'iva',index:'iva', width:110,editable:false,editoptions:{size:10}},
           {name:'descrizione',index:'descrizione', width:110,editable:false,editoptions:{size:10}},
           {name:'utente',index:'utente', width:90,editable:false,editoptions:{size:15}},
           {name:'indirizzo',index:'indirizzo', width:110, align:"right",editable:false,editoptions:{size:10}},
           {name:'citta',index:'citta', width:110, align:"right",editable:false,editoptions:{size:10}},        
           {name:'cap',index:'cap', width:40,align:"right",editable:false,editoptions:{size:10}},
        {name:'provincia',index:'provincia', width:60,align:"right",editable:false,editoptions:{size:10}},
        {name:'telefono',index:'telefono', width:90,align:"right",editable:false,editoptions:{size:10}},
        {name:'email',index:'email', width:160,align:"right",editable:false,editoptions:{size:10}},
        {name:'attivo',index:'attivo',width:55,align:'center',editable:true,edittype:"checkbox",editoptions:{value:"Yes:1;No:0"}},
        {name:'cancellato',index:'cancellato',width:60,align:'center',editable:true,edittype:"checkbox",editoptions:{value:"Yes:1;No:0"}}      
        ],
       rowNum:10,
       rowList:[10,20,30],
       pager: '#pagernav',
       sortname: 'iva',
    viewrecords: true,
    sortorder: "asc",
    width: 690,
    shrinkToFit: false,
    height: "100%",
    caption:"Utenti d'abilitare",
    editurl:"abilitare.php"
    
});
jQuery("#navgrid").jqGrid('navGrid','#pagernav',{edit:true,add:false,del:false,search:false},
{}, //options
{height:'auto',reloadAfterSubmit:true}, // edit options
{height:540,reloadAfterSubmit:false}, // add options
{reloadAfterSubmit:false}, // del options
{} // search options
);

<?php
include('../inc/db.php');
if (isset($_POST["oper"])) {
    if ($_POST["oper"] == "add") {
    } elseif ($_POST["oper"] == "edit") {
        $editSQL = sprintf("update clienti set attivo = %s, cancellato = %s
            where iva = %s and utente = %s",
                        GetSQLValueString($_POST['attivo'], "int"),
                        GetSQLValueString($_POST['cancellato'], "int"),
                        GetSQLValueString($_POST['iva'], "text"),
                        GetSQLValueString($_POST['utente'], "text"));
        $Result = mysql_query( $editSQL ) or die("Couldn t execute query.".mysql_error());
    } elseif ($_POST["oper"] == "del") {
        $deleteSQL = sprintf("delete from users where idusers = %s",
                        GetSQLValueString($_POST['id'], "int"));
        $Result = mysql_query($deleteSQL, $metrics) or die(mysql_error());
    }
}

function GetSQLValueString($theValue, $theType, $theDefinedValue = "", $theNotDefinedValue = "")
{
  $theValue = (!get_magic_quotes_gpc()) ? addslashes($theValue) : $theValue;

  switch ($theType) {
    case "text":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;    
    case "long":
    case "int":
      $theValue = ($theValue != "") ? intval($theValue) : "NULL";
      break;
    case "double":
      $theValue = ($theValue != "") ? "'" . doubleval($theValue) . "'" : "NULL";
      break;
    case "date":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;
    case "defined":
      $theValue = ($theValue != "") ? $theDefinedValue : $theNotDefinedValue;
      break;
  }
  return $theValue;
}
?>