How to update database through swing and how to resolve it?

Here is my code. There is no problem with my insert and delete query. But i m unable to update the database (HINT: ITS SHOWING ERROR MESSAGE UNKNOWN WHERE CLAUSE)

The problem is with UPDATION part.
My database Name:tut.
My table name:FilesManagement1.

I dont have much knowledge about MYSQL. What do I have to do now?

import java.awt.event.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import javax.swing.*;

public class Work extends JFrame{
 JLabel JL_Filechooser,JL_Filetype,JL_Target,JL_Filescompleted;
 JTextField JT_Filechooser,JT_Filetype,JT_Target,JT_Filescompleted;
 JButton btn_insert,btn_update,btn_delete;
 public Work(){
     super("INSERT UPDATE DELETE");
     JL_Filechooser = new JLabel("File chooser:");
     JL_Filetype = new JLabel("File type:");
     JL_Target = new JLabel("Target:");
     JL_Filescompleted = new JLabel("Files completed:");
     JL_Filechooser.setBounds(20, 20, 100, 20);
     JL_Filetype.setBounds(20, 50, 100, 20);
     JL_Target.setBounds(20, 80, 100, 20);
     JL_Filescompleted.setBounds(20, 110, 100, 20);

     JT_Filechooser = new JTextField(20);
     JT_Filetype = new JTextField(20);
     JT_Target = new JTextField(20);
     JT_Filescompleted = new JTextField(20);
     JT_Filechooser.setBounds(130,20,150,20);
     JT_Filetype.setBounds(130, 50, 150, 20);
     JT_Target.setBounds(130, 80, 150, 20);
     JT_Filescompleted.setBounds(130, 110, 150, 20);
     btn_insert = new JButton("Insert");
     btn_update = new JButton("Update");
     btn_delete = new JButton("Delete");
     btn_insert.setBounds(300, 50, 80, 20);
     btn_update.setBounds(300, 80, 80, 20);
     btn_delete.setBounds(300, 110, 80, 20);     
     setLayout(null);
     add(JL_Filechooser);
     add(JL_Filetype);
     add(JL_Target);
     add(JL_Filescompleted);
     add(JT_Filechooser);
     add(JT_Filetype);
     add(JT_Target);
     add(JT_Filescompleted);
     add(btn_insert);
     add(btn_update);
     add(btn_delete);

   //button insert
    btn_insert.addActionListener(new  ActionListener() {

         public void actionPerformed(ActionEvent e) {
         try{
             theQuery("insert into FilesManagement1 (Filechooser,Filetype,Target,Filescompleted) values('"+JT_Filechooser.getText()+"','"+JT_Filetype.getText()+"',"+JT_Target.getText()+",'"+JT_Filescompleted.getText()+"')");
         }
         catch(Exception ex){}
         }
     });

        //button update
        btn_update.addActionListener(new  ActionListener() {

         public void actionPerformed(ActionEvent e) {
         try{

           theQuery("update FilesManagement1 set Filechooser = '"+JT_Filechooser.getText()+"',Filetype = '"+JT_Filetype.getText()+"', Target = "+JT_Target.getText()+" where Filechooser = "+JT_Filechooser.getText());
         }
         catch(Exception ex){}
         }
     });

         //button delete
        btn_delete.addActionListener(new  ActionListener() {

         public void actionPerformed(ActionEvent e) {
         try{

             theQuery("delete from FilesManagement1 where Filechooser = "+JT_Filechooser.getText());
         }
         catch(Exception ex){}
         }
     });


     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     setVisible(true);
     setLocationRelativeTo(null);
     setSize(500,200);

 }

 //function to execute the insert update delete query
  public void theQuery(String query){
      Connection con = null;
      Statement st = null;
      try{
          con = DriverManager.getConnection("jdbc:mysql://localhost/tut","root","root");
          st = con.createStatement();
          st.executeUpdate(query);
          JOptionPane.showMessageDialog(null,"YOUR FILES HAS BEEN UPDATED");
      }catch(Exception ex){
          JOptionPane.showMessageDialog(null,ex.getMessage());
      }
  }


     public static void main(String[] args){       
         new  Work();
     }
}