Extract sum of values from database in java

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Java

I want to display sum of amount in textfield but amount fetching from database..Here I tried this code but only 0.0 displays in textfield...Dint get actual amount.

What I have tried:

try
            {
                String t= (String)client.getSelectedItem();   //client = JCombobox
                String query1="select total(Amount) from enquiry where `client`= ?";
                PreparedStatement p=conn.prepareStatement(query1);
                p.setString(1,tfsum.getText());    //tfsum = textfield whr sum will displays
                ResultSet r=p.executeQuery();

                if(r.next())
                {

                    String s=r.getString("total(Amount)");

                    tfsum.setText(s);

                }
                r.close();
                p.close(); 

            }
            catch(Exception d)
            {
                d.printStackTrace();
            }



        }