How To Make The Database Results To Appear When I Search The First Letter Or Number?

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Java

GUI

Eclipse

JComboBox comboBox = new JComboBox();
      comboBox.setModel(new DefaultComboBoxModel(new String[] {"DateSave", "Category", "Amount", "Content"}));
      comboBox.setBounds(250, 476, 107, 26);
      add(comboBox);
      
      textFieldSearch = new JTextField();
      textFieldSearch.addKeyListener(new KeyAdapter() {
      	@Override
      	public void keyPressed(KeyEvent arg0) {
      		try{
    			String selection = (String)comboBox.getSelectedItem();
    			Class.forName("org.gjt.mm.mysql.Driver");
    			String url ="";
    			url = "jdbc:mysql://localhost/project"; 
    			Connection con = DriverManager.getConnection(url, "ITUser", "user"); 
    			String query="Select * from saving where "+selection+" =?";
    			
    			PreparedStatement pst= (PreparedStatement) con.prepareStatement(query);
    			pst.setString(1,textFieldSearch.getText());
    			
    			ResultSet rs=pst.executeQuery();
    			
    			Savingtable.setModel(DbUtils.resultSetToTableModel(rs));
    			String search =	textFieldSearch.getText();
    			if(search.length() == 0){    //to make back normal when search is empty
    				setTableModelFromDB();
    				scrollPane.setViewportView(Savingtable);
    				scrollPane.setColumnHeaderView(Savingtable.getTableHeader());
    			}

    			while(rs.next())
    			{
    		        }

    			pst.close();
    	              }catch(Exception ex){
    		ex.printStackTrace();
    	}
      	}
      });
      textFieldSearch.setBounds(716, 474, 146, 26);
      add(textFieldSearch);
      textFieldSearch.setColumns(10);

I can search from my database from my textField but it must be typed in full text, the result will then appear.For example, the amount is 700,i must type 700 then the result can appear. How to make database result to appear when i search the first letter or number :(