Incorrect syntax near '='.

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.IO;
using System.Data.SqlClient;

public partial class Payment : System.Web.UI.Page
{
    SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCafe.mdf;Integrated Security=True;User Instance=True");
    SqlCommand cmd;

    protected void Page_Load(object sender, EventArgs e)
    {
       // Response.Write("<script>alert('arr cnt= " + Session["UserId"].ToString() + " ')</script>");

     
        //To show data from billing address
        cmd = new SqlCommand("SELECT * FROM Billing_Address WHERE User_ID=" + Session["UserId"].ToString()+"", cn);
        cn.Open();
        SqlDataReader DR = cmd.ExecuteReader();

  
        if (DR.HasRows)
        {
            DR.Read();
            
            
            lblname.Text = DR["First_Name"] + DR["Last_Name"].ToString();
            Label8.Text = DR["Address"].ToString();
            Label10.Text = DR["Zip"].ToString();
            Label12.Text = DR["City"].ToString();
            Label14.Text = DR["State"].ToString();
            Label16.Text = DR["Country"].ToString();


        }
        else
        {
            Response.Write("<script>alert('!!!......Record Not Found .....!!!')</script>");
        }
        DR.Close();

        cn.Dispose();
        cn.Close();
        cmd.Dispose();


        //To show data from user table

        SqlConnection cn1 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCafe.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd1;

        cmd1 = new SqlCommand("SELECT * FROM User_table WHERE User_ID=" + Session["UserId"].ToString() + "", cn1);
        cn1.Open();
        SqlDataReader DR1 = cmd1.ExecuteReader();



        if (DR1.HasRows)
        {
            DR1.Read();

            lblemail.Text = DR1["Email_ID"].ToString();
            

        }
        else
        {
            Response.Write("<script>alert('!!!......Record Not Found1 .....!!!')</script>");
        }
        DR1.Close();

        cn1.Dispose();
        cn1.Close();
        cmd1.Dispose();



        //To show data from Order_master 
        //Response.Write("<script>alert('"+DateTime.Now.Date+"')</script>");


        SqlConnection cn2 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCafe.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd2;

        cmd2 = new SqlCommand("SELECT * FROM Order_Master WHERE User_ID=@User_Id and Order_Date=@Order_date",cn2);
        cmd2.Parameters.AddWithValue("User_Id", Session["UserId"].ToString());
        cmd2.Parameters.AddWithValue("Order_Date", DateTime.Now.Date);
        cn2.Open();

        SqlDataReader DR2 = cmd2.ExecuteReader();

        int OrN=0;

        if (DR2.HasRows)
        {
            DR2.Read();

            lblbillno.Text = DR2["Order_No"].ToString();
            txtamount.Text = DR2["GTotal_Amount"].ToString();
            OrN = Int32.Parse( DR2["Order_No"].ToString());


        }
        else
        {
            Response.Write("<script>alert('!!!......Record Not Found2 .....!!!')</script>");
        }
        DR2.Close();

        cn2.Dispose();
        cn2.Close();
        cmd2.Dispose();


        //To Show data from Order Details

       
        SqlConnection cn3 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCafe.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd3;

        cmd3 = new SqlCommand("SELECT * FROM My_Cart PRODUCT,FLAVOURS,SIZE,PRICE,QUANTITY,TOTAL_AMOUNT FROM PAYMENT WHERE Order_No=" + OrN + "", cn3);
        cn3.Open();


        SqlDataReader DR4 = cmd3.ExecuteReader();
        DataTable PDT = new DataTable();
        PDT.Load(DR4);
        GridView2.DataSource = PDT;
        GridView2.DataBind();
        cn3.Dispose();
        cn3.Close();
        cmd3.Dispose();



    }


    protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
    {
        SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCafe.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd;
        if (Page.IsValid)
        {
            if (Session["UserName"].ToString() == "")
            {
                Response.Redirect("Expire.aspx");
            }
            else
            {
                //To insert into Billing Address
                cmd = new SqlCommand("INSERT INTO CARD_DETAILS (CARD_NO,EXPIRATION,CARD_TYPE,CVV,USER_ID,ORDER_NO)values(@CARD_NO,@EXPIRATION,@CARD_TYPE,@CVV,@USER_ID,@ORDER_NO)", cn);
                cmd.Parameters.AddWithValue("@CARD_NO", TextBox10.Text);
                string exp=DropDownList4.Text+"-"+DropDownList5.Text;
                cmd.Parameters.AddWithValue("@EXPIRATION", exp);
                cmd.Parameters.AddWithValue("@CARD_TYPE", DropDownList6.Text);
                cmd.Parameters.AddWithValue("@CVV", TextBox11.Text);
                cmd.Parameters.AddWithValue("@USER_ID", Session["UserId"].ToString());
                cmd.Parameters.AddWithValue("@ORDER_NO",lblbillno.Text );
                
                cn.Open();
                int res = cmd.ExecuteNonQuery();
                //if (res == 1)
                //{
                //    Response.Write("<script>alert('!!!......Record Saved .....!!!')</script>");
                //}
                //else
                //{
                //    Response.Write("<script>alert('!!!......Record Not Saved .....!!!')</script>");
                //}
                cn.Dispose();
                cn.Close();
                cmd.Dispose();
                Response.Redirect("~/Thank_You.aspx");
            }
        }
    }
    protected void GridView2_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
}