I have some problem in sqlcommand where condition to implement the c# coding

Question

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ccc"].ConnectionString); con.Open(); SqlCommand cmd = new SqlCommand("select [Town Name] from town where '" + DropDownList1.SelectedItem.Text + "' <= '" + TextBox1.Text + "'", con); //ListBox1.Text = cmd.ExecuteScalar().ToString(); TextBox4.Text = cmd.ExecuteScalar().ToString(); con.Close(); In This coding after Where condition not use to textbox,label,dropdownlist,etc how can I use textbox,label,dropdownlist,etc send me answer quickly to [email protected]