Update Payment in database

SqlCommand cmd = new SqlCommand("UPDATE Bank SET Payment = '(Payment - "+tprice.Text +")' WHERE NICNO = '" + FN.Text + "'", con);

string sqlCmdText = "UPDATE Bank  SET Payment = (Payment - " + tprice.Text + ") WHERE NICNO = '" + FN.Text + "'";
SqlConnection conn = new SqlConnection("YourWebConfigConnectionStringID");
using (SqlCommand cmd = new SqlCommand(sqlCmdText, conn))
{
    cmd.CommandType = CommandType.Text;
    try
    {
        conn.Open();
        cmd.ExecuteNonQuery();
    }
    catch (SqlException)
    {
        // You want to catch your exception here?...
    }
    finally
    {
        cmd.Dispose();
        conn.Dispose();
        // No need to close cmd and conn will automatically close by using...
    }
 }