theQuery("update gkkdb set CUST_ID='"+t1.getText()+"', CUST_PHONE="+t3.getText()+",CUST_CAT='"+t4.getText()+"',ST_DATE='"+t5.getText()+"',ADV="+t6.getText()+",END_DATE='"+t7.getText()+"',ADDR='"+t8.getText()+"' where CUST_NAME="+t2.getText());

public void theQuery(String query)
{
Connection con = null;
Statement st= null;
try{
    DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
    con = DriverManager.getConnection("jdbc:oracle:thin:@Localhost:1521:xe","system","qwerty");
    System.out.println("Database connected");
    st= con.createStatement();
    st.executeUpdate(query);
    JOptionPane.showMessageDialog(null,"Customer Updated!");
    clear();
    } catch(Exception e)
    {
    JOptionPane.showMessageDialog(null,e.getMessage());
    }
    }