我想把两个表的数据合并到一个表中，并显示两个表的数据。我已经有了加载一个表的函数。有人能修改这个函数代码来得到两个表吗？我只是一个初学者。

模型_用户.php

public function getUserGroup($userId = null) 
    {
        if($userId) {
            $sql = "SELECT * FROM user_group WHERE user_id = ?";
            $query = $this->db->query($sql, array($userId));
            $result = $query->row_array();

            $group_id = $result['group_id'];
            $g_sql = "SELECT * FROM groups WHERE id = ?";
            $g_query = $this->db->query($g_sql, array($group_id));
            $q_result = $g_query->row_array();
            return $q_result;
        }
    }

控制器用户.php

public function index()
    {
        if(!in_array('viewUser', $this->permission)) {
            redirect('dashboard', 'refresh');
        }

        $user_data = $this->model_users->getUserData();

        $result = array();
        foreach ($user_data as $k => $v) {

            $result[$k]['user_info'] = $v;

            $group = $this->model_users->getUserGroup($v['id']);
            $result[$k]['user_group'] = $group;
        }

        $this->data['user_data'] = $result;

        $this->render_template('users/index', $this->data);
    }