private string _returncall;
    protected void Page_Load(object sender, EventArgs e)
    {

        string referecnce = Page.ClientScript.GetCallbackEventReference(this, "arg", "GetDettagli", "context");
        string script = "function UseCallback(arg,context)" + "{" + referecnce + ";" +"}";

        Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "UseCallback", script, true);


    }

    #region ICallbackEventHandler Members

    public string GetCallbackResult()
    {
       
        return _returncall;
            
    }

    public void RaiseCallbackEvent(string eventArgument)
    {
       
        SqlConnection conn = new SqlConnection();
        conn.ConnectionString=ConfigurationManager.ConnectionStrings["UglConnessione"].ConnectionString;
        SqlCommand cmd = new SqlCommand("SELECT cl.nome,cl.cognome,cl.indirizzo,cl.dataInserimento FROM Cliente as cl WHERE cognome = '" + eventArgument + "'",conn);
        cmd.Connection = conn;
        SqlDataReader dr;
        conn.Open();

        dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        
        string[] cliente=new string[4];
        while (dr.Read())
        {
            cliente[0] = dr["nome"].ToString();
            cliente[1] = dr["cognome"].ToString();
            cliente[2] = dr["indirizzo"].ToString();
            cliente[3] = dr["dataInserimento"].ToString();
        }
        _returncall = String.Join(" ", cliente);
    }

    #endregion