从MySql数据库获取UnitPrice的值时出错

Question

I am developing a Medical Store Management System In Java using MySQL database,there is a little issue in calculating the total bill,it's not fetching the UnitPrice from the Database.Please help me if you know.

     Connection con = Database.DBConnect();
     String sql = "select UnitPrice from medicines where MedicineName= ?";
     try{
         st = con.prepareStatement(sql);
         st.setString(1,(ProductName.getSelectedItem().toString()));
         rs = st.executeQuery();
         while(rs.next()){
             int result = Integer.parseInt(EnterQuantity.getText());
             Double   Bill = result * rs.getDouble(sql);
             JOptionPane.showMessageDialog(null,"The total Bill = " +Bill);
         }

      } catch (SQLException e) {
          JOptionPane.showMessageDialog(null,e);
    }

Answer 1

Double   Bill = result * rs.getDouble(sql);

Why do you put your query as a parameter of the getDouble() - function. It has to take the column name as far as I know.

Also, just don't start your variable-names with upper case letters.

Answer 2

Double Bill = result * rs.getDouble(sql);???? try to check this