//Kết nối tới CSDL

    public Connection connect() {
        Connection con = null;
        String url = "jdbc:mysql://localhost:3306/QLNV";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection(url, "root", "123456");
            } catch (Exception e) {
        e.printStackTrace();
        }
        return con;
    }
    //select
    public ResultSet select(String sql, Connection connect) {
        ResultSet rs = null;
        try {
            rs = connect.createStatement().executeQuery(sql);
        }catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
    //Update
    public int update(String sql, Connection connect) {
    int rs = 0;
    try {
        rs = connect.createStatement().executeUpdate(sql);
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return rs;
    }
    //Dong ket noi CSDL
    public void closeConnection(Connection connect) {
        try {
        connect.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public void LoadDataCmbCty() throws SQLException
    {
        String s1 = cmbMaCT.getItemAt(cmbMaCT.getSelectedIndex());
        Connection con = connect();
        ResultSet rs = select("select MaCty from CONGTY", con);

        while(rs.next())
        {
            cmbMaCT.addItem(rs.getString("MaCty"));
        }

    }
    public int checkNumberString(String number) {
        Pattern pattern = Pattern.compile("^[0-9]*$");
        Matcher matcher = pattern.matcher(number);
        if (!matcher.matches())
            return 0;//"Chuỗi nhập vào không phải là số!";
         else return 1;
        }