mysql如何向mongodb转化

/** * 校验Email是否注册 * @param email * @return * @throws SQLException */public boolean ajaxValidateEmail(String email) throws SQLException { String sql = "select count(1) from t_user where email=?"; Number number = (Number)qr.query(sql, new ScalarHandler(), email); return number.intValue() == 0;}/** * 用户名注册校验 * @param loginname * @return */public boolean ajaxValidateLoginname(String loginname) { try { return userDao.ajaxValidateLoginname(loginname); } catch (SQLException e) { throw new RuntimeException(e); }}/** * Email校验 * @param email * @return */public boolean ajaxValidateEmail(String email) { try { return userDao.ajaxValidateEmail(email); } catch (SQLException e) { throw new RuntimeException(e); }}这是用mysql语法写的，如果用的是mongo该怎么写呢，求教