按列数据获取sql查询结果组

Question

我有两张表maintenance_owner，maintenance_users 下面是我的表结构 这是维护用户表 

这是维护所有者表

现在我可以使用此代码获取所有用户

    $this->db->select('mu.*, mo.id_land_owner as mu_owner, mo.group_name, mo.id_mu');

    $this->db->from('maintenance_users as mu');

    $this->db->join('maintenance_owner as mo','mu.id_maintenance = mo.id_mu');

    $this->db->where('mo.id_land_owner', $land_owner_id);

    return $this->db->get()->result();

它返回

[0] => stdClass Object

    (

        [id_maintenance] => 170

        [full_name] => 

        [username] => [e-mail]

        [password] => 

        [token] => 914c001251a1ab018e5eb51923e8f6cc

        [mu_owner] => 152

        [group_name] => Cleaner

        [id_mu] => 170

    )

[1] => stdClass Object

    (

        [id_maintenance] => 176

        [full_name] => 

        [username] => [e-mail]

        [password] => 

        [token] => 579faa456520656fcc24be047ca6a3bf

        [mu_owner] => 152

        [group_name] => 

        [id_mu] => 176

    )

[2] => stdClass Object

    (

        [id_maintenance] => 175

        [full_name] => 

        [username] => [e-mail]

        [password] => 

        [token] => d2f6b180a6a7bb32ecd26ffe0297f8f5

        [mu_owner] => 152

        [group_name] => 

        [id_mu] => 175

    )

但我需要得到这样的结果

    [0] => stdClass Object

    (

        [id] => 30

        [id_land_owner] => 152

        [group_name] => Cleaner

        [group_users] => [e-mail],[e-mail],[e-mail],[e-mail]

    )

[1] => stdClass Object

    (

        [id] => 29

        [id_land_owner] => 152

        [group_name] => Gardener

        [group_users] => [e-mail],[e-mail],[e-mail]

    )

只需要使用 sql 查询来执行此操作我正在使用 codeigniter fraework