这是我的代码，我在网上找了很久，也知道它错的原因，但我还是不能改好它。还希望帮我优化一下我的代码。谢谢...


        string cnsql = "server=.;database=wuliu;Integrated Security=SSPI";
        SqlConnection mycon = new SqlConnection(cnsql);
        mycon.Open();
        string str = "select * from dingdan where  ID = '" + Session ["danhao"] + "'";
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = mycon;
        cmd.CommandText = "select * from dingdan where  ID = '" + Session["danhao"] + "'";
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            SqlDataAdapter sda = new SqlDataAdapter(str, mycon);
            DataSet ds = new DataSet();
            sda.Fill(ds, "mytb");
            DataView dv = ds.Tables["mytb"].DefaultView;
            GridView1.DataSource = dv;
            GridView1.DataBind();
            dr.Close();
        }
        else {
            Response.Write("<script language='javascript'> alert('查询不到你的订单号，请电我们公司电话核实') ;window.location.href = 'index.aspx';</script>");
        }
        mycon.Close();

        string cnsql = "server=.;database=wuliu;Integrated Security=SSPI";
        SqlConnection mycon = new SqlConnection(cnsql);
        mycon.Open();
        string str = "select * from dingdan where  ID = '" + Session ["danhao"] + "'";
        SqlDataAdapter sda = new SqlDataAdapter(str, mycon);
        DataSet ds = new DataSet();
        sda.Fill(ds, "mytb");
        if(ds.Tables["mytb"].Rows.Count>0)
        {
            DataView dv = ds.Tables["mytb"].DefaultView;
            GridView1.DataSource = dv;
            GridView1.DataBind();
            dr.Close();
        }
                else {
            Response.Write("<script language='javascript'> alert('查询不到你的订单号，请电我们公司电话核实') ;window.location.href = 'index.aspx';</script>");
        }
        mycon.Close();