Question

For school I’m working on a program that connects to a MySQL database and perform queries such as an ATM machine might.

So far I’ve made a simple program where I’ve been putting my connection code in the submit button, but now I need to support many different buttons for balance query, withdrawal, etc.

For my initial screen where the user enters their login and PIN I have the following code, but I’m kind of lost as to how I can do these queries under other buttons with the variables I have in this button:

private void bSubmitActionPerformed(java.awt.event.ActionEvent evt) {                                        
    String login = jLogin.getText();
    String pin = jPin.getText();


    try {
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost/bankaccount", "root", "password");

        Statement st = (Statement) con.createStatement();
        PreparedStatement ps;
        String sqlCommand;
        ResultSet rs;

        sqlCommand = "SELECT * FROM accounts WHERE loginID= '" + login + "' AND pin='" + pin + "'";

        rs = st.executeQuery(sqlCommand);

        if (rs.next()) {

            do {

                card2.setVisible(true);
                card1.setVisible(false);



            } while (rs.next());
        } else {
            jWarning.setText("please try again");
        }





    } catch (Exception e) {
    }
}

Answer 1

    public ResultSet execute(String sqlCommand ){

    ResultSet rs = null;

    try {
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost/bankaccount", "root", "password");

        Statement st = (Statement) con.createStatement();
        PreparedStatement ps;


        rs = st.executeQuery(sqlCommand);


    } catch (Exception e) {
    }

    return rs;

}


public void submitButton1(){
     String login = jLogin.getText();
    String pin = jPin.getText();

ResultSet rs = execute("SELECT * FROM accounts WHERE loginID= '" + login + "' AND pin='" + pin + "'");

   /// do whatever with your rs

}

public void submitButton2(){
     String login = jLogin.getText();
    String pin = jPin.getText();

ResultSet rs = execute("more sql");

   /// do whatever with your rs

}

appending the update method:

public int update(String sqlCommand ){

       int affected_rows = 0;
        try {
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost/bankaccount", "root", "password");

            Statement st = (Statement) con.createStatement();                

            affected_rows = st.executeUpdate(sqlCommand);


        } catch (Exception e) {
        }

        return affected_rows;

    }

The update method also can be used to insert and delete. An update statament could be something like this:

update accounts  
set columnA = "a value",  
columnB = "other value"  
where loginID = 4;