Troubles with PreparedStatement and ResultSet when executing SELECT query?

Question

There are no problems with UPDATE and INSERT query, troubles only with SELECT, here all code:

try {
        String nCard = jTextField1.getText();
        String deprecate = jTextField2.getText();
        DriverManager.registerDriver(new com.mysql.jdbc.Driver());
        String url = "jdbc:mysql://localhost:3306/visits";
        Connection conn1 = DriverManager.getConnection(url, "root", "");

        PreparedStatement pstmt = conn1.prepareStatement("INSERT INTO `visits`.`transaction` (`numbercard`, `deprecate`) VALUES (?, ?)");
        pstmt.setString(1, nCard);
        pstmt.setString(2, deprecate);
        pstmt.executeUpdate();

        DrawTable();

        PreparedStatement pstmt1 = conn1.prepareStatement("SELECT `balance` FROM `visitor` WHERE `cardID`=?");
        int nCardInt = Integer.parseInt(nCard);
        pstmt1.setInt(1, nCardInt);
        ResultSet rs1 = pstmt1.executeQuery();
        int tempBonus=rs1.getInt(1);
        tempBonus-=Integer.parseInt(deprecate);
        String bonusString = String.valueOf(tempBonus);

        PreparedStatement pstmt2 = conn1.prepareStatement("UPDATE `visitor` SET `balance`=? WHERE cardID=?");
        pstmt2.setString(1, bonusString);
        pstmt2.setString(2, nCard);
        pstmt2.executeUpdate();
    } catch (SQLException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    }

I need only 1 cell by ID to manipulate with it, "SELECT balance FROM visitor WHERE cardID=?". If anyone will suggest easyer methods, I would be very grateful.

Answer 1

You forgot the call to next(), which will advance the cursor to the first row, if present.

A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.

if (rs1.next())
{
    int tempBonus=rs1.getInt(1);
}