Question

I have written a code to delete a record in a MySQL database from my Java Program. It compiles and runs it successfully, but the record is still in the datbase. Any suggestions?

JButton btnDelete = new JButton("Delete");
btnDelete.addActionListener(new ActionListener() {

    public void actionPerformed(ActionEvent arg0) {

        try {

            Object[] options = {"Yes", "No"};
            Component form = null;
            int n = JOptionPane.showOptionDialog(form, "Do you like to delete the record for Student ID: " +
                    textField_16.getText() + " ?", "Exit Confirmation", JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options);

            if(n == JOptionPane.YES_OPTION) {

                String mock = textField_16.getText();   

                String sql = "DELETE FROM mockexam WHERE MockID =?";
                PreparedStatement prest = con.prepareStatement(sql);
                prest.setString(1, mock);
                int val = prest.executeUpdate();
                JOptionPane.showMessageDialog(frmDeleteMock, "The record has been deleted successfully.");
            }
        } 
        catch (SQLException e) {
            e.printStackTrace();
            JOptionPane.showMessageDialog(frmDeleteMock, "Record couldn't be deleted. Please try again.");
        }       
    }
});

btnDelete.setBounds(45, 235, 89, 23);
panel_1.add(btnDelete);

Answer 1

prest.setString(1, "MockID");

You are looking for a MockID equal to MockID I assume you want to delete a entry with a certain ID use:

String mockID = "2"; //Set this however you want to set it.
prest.setString(1, mockID);
int val = prest.executeUpdate();
//Check val for what happened.