Update Specific Rows In MySQL Database?

Question

greetings all
i have MySQL database named library contains a table named books with the attributes:name,amount,price,cat_id
and i want to update all the names,amount,prices for specific cat_id
so i used the following query:
PreparedStatement ps = connection.prepareStatement("UPDATE books SET name = ?,amount = ?,price = ? Where cat_id = "+1);
and get the question marked values from the JTable named table_science
                for(int i = 0 ; i< dtm_science.getRowCount(); i++){                                         ps.setString(1,(String)table_science.getValueAt(i,2));                                  ps.setInt(2,(Integer)table_science.getValueAt(i,1));                 ps.setInt(3,(Integer)table_science.getValueAt(i,0));                                 ps.executeUpdate();                                                                                                                        }                         ps.close();             connection.close();
the code doesn't work properly
it takes the values in the last row in the jtable and set them for all attributes with cat_id=1
meaning if you have 3 rows in the jtable named table_science which have cat_id=1 and the columns:
name,amount,price
abc,5,300
efg,6,400
mno,6,900
and when i exceute the update query all the fields in the database which have cat_id=1 would be set to mno,6,900
meaning that the table_science would be:
mno,6,900
mno,6,900
mno,6,900
is there's an error in the code?
or what's the problem?
thanks in advance

Answer 1

the database name:test
table name:books
attributes:name,amount,price,cat_id
description:several names may have the same cat_id
goal:when the user presses update button
all names,amounts,prices with cat_id=1 in the database is updated with the JTable values name,amount,price
problem:when changing values in the JTable and trying to update all names,amounts,prices with cat_id=1 is set to the last row values in the jtable?
here's the whole code:
import javax.swing.*;
import javax.swing.table.*;
import java.awt.Dimension;
import java.awt.*;
import javax.swing.JFrame;
import java.awt.event.*;
import javax.swing.JTable;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSetMetaData;
import java.sql.ResultSet;
import java.sql.Statement;
class table_update extends JPanel {
    static DefaultTableModel dtm1;
    static JTable table1;
    static JFrame frame;
    public table_update() {
        super(new GridLayout(1, 1));
        dtm1 = new DefaultTableModel();
        dtm1.addColumn("ID");
        dtm1.addColumn("Name");
        dtm1.addColumn("Amount");
        dtm1.addColumn("Price");
        table1 = new JTable(dtm1) {
            public Class getColumnClass(int column) {
                return getValueAt(0, column).getClass();
        JScrollPane scrollPane1 = new JScrollPane(table1);
        JButton Update = new JButton("Update");
        table1.putClientProperty("terminateEditOnFocusLost", Boolean.TRUE);
        table1.setPreferredScrollableViewportSize(new Dimension(410, 160));
        JPanel panel1 = new JPanel(new FlowLayout());
        panel1.add(scrollPane1);
        panel1.add(Update);
        Update.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event20) {
                update_db();
                frame.dispose();
                createAndShowGUI();
        //reading from databse
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection c1 = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", "");
            Statement s1 = c1.createStatement();
            ResultSet rs1 = s1.executeQuery("SELECT name,amount,price from books where cat_id=1");
            int id1 = 0;
            while (rs1.next()) {
                id1++;
                Object[] obj = {id1, rs1.getString("name"), rs1.getInt("amount"), rs1.getInt("price")};
                dtm1.addRow(obj);
            c1.close();
        } catch (Exception e) {
            e.printStackTrace();
        table1.setModel(dtm1);
        setLayout(new BorderLayout());
        add(panel1, BorderLayout.CENTER);
    public static void createAndShowGUI() {
        frame = new JFrame("Update DB");
        frame.setSize(500, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new table_update());
        frame.setResizable(false);
        frame.setVisible(true);
        JTable table1 = new JTable();
        table1.setModel(new DefaultTableModel(new Object[][][][]{}, new String[]{"id", "name", "amount", "price"}) {
            Class[] types = new Class[]{
                java.lang.Integer.class, java.lang.String.class, java.lang.Integer.class, java.lang.Integer.class
            public Class getColumnClass(int columnIndex) {
                return types[columnIndex];
    public static void update_db() {
        Connection c = null;
        PreparedStatement ps = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test?requireSSL=false&useUnicode=true&characterEncoding=utf8";
            c = DriverManager.getConnection(url, "root", "");
            ps = c.prepareStatement("UPDATE books SET name = ?,amount = ?,price = ? WHERE cat_id = 1 ");
            for (int i = 0; i < dtm1.getRowCount(); i++) {
                ps.setString(1, (String) table1.getValueAt(i, 1));
                ps.setInt(2, (Integer) table1.getValueAt(i, 2));
                ps.setInt(3, (Integer) table1.getValueAt(i, 3));
                ps.executeUpdate();
            ps.close();
            c.close();
        } catch (Exception ex) {
            ex.printStackTrace();
    public static void main(String[] args) {
        createAndShowGUI();
}