protected void Page_Load(object sender, EventArgs e) { try { string str = Request.QueryString["id"]; if (Request.QueryString["id"] == null) { Response.Redirect("display_item.aspx"); } else if (string.IsNullOrEmpty(Request.QueryString["id"].ToString())) { Response.Redirect("display_item.aspx"); } else { id = Convert.ToInt32(Request.QueryString["id"].ToString()); if (!(con.State == ConnectionState.Open)) { con.Open(); } SqlCommand cmd = new SqlCommand(); cmd.Connection = con; // cmd.CommandText = "SELECT * FROM product WHERE Quantity > 0 AND id=" + id + ";"; cmd.CommandText = "SELECT * FROM product WHERE id=" + id + ";"; cmd.ExecuteNonQuery(); DataTable dt = new DataTable(); SqlDataAdapter sda = new SqlDataAdapter(cmd); sda.Fill(dt); L1.DataSource = dt; L1.DataBind(); } qtyvalue = getQty(id); if (qtyvalue == 0) { lblQty.Visible = false; tbQty.Visible = false; btnAddtoCart.Visible = false; lblErr.Text = "Out of Stock!"; } } catch (Exception ex) { Response.Write(ex.ToString()); } }