Question

我正在尝试从视频表中获取userIds列表。此表包含上传用户的媒体文件。这是我的代码

        $this->db->select("videos.user_id as userId");
        $this->db->limit('10', $document['offset']);
        $this->db->group_by('userId');
        $this->db->order_by('id','desc');

        $recentUploads = $this->db->get('videos')->result_array();
        if (!empty($recentUploads)) 
        {
            foreach ($recentUploads as $record) 
            {
                $totalPostMedia = $obj->totalPostMedia($record);
                $record['totalPostMedia'] = $totalPostMedia;

                $resData = $this->db->select("username, profileImage")->from('users')->where('id', $record['userId'])->get()->row_array();
                $record['uploadBy'] = $resData['username'];
                $record['profileImage'] = "http:...com/profileImage/".$resData['profileImage'];

                $Mydata[] = $record;
            }
        }

结果get缺少表中的一些userIds。我也试过了$this->db->distinct()。仍然得到相同的结果。我获得没有重复项的结果的唯一方法是删除$this->db->order_by('id','desc');或将其asc代替desc。但我想从表中获得最新记录。我该怎么做呢？难道我做错了什么？任何帮助将非常感激。

Answer 1

试试这个

$this->db->select("videos.user_id as userId");
$this->db->from("videos");
$this->db->group_by('userId');
$this->db->order_by('id','desc');
$this->db->limit('10', $document['offset']);

$recentUploads = $this->db->get()->result_array();
if (count($recentUploads)>0) 
{
    foreach ($recentUploads as $record) 
    {
        $totalPostMedia = $obj->totalPostMedia($record);
        $record['totalPostMedia'] = $totalPostMedia;

        $resData = $this->db->select("username, profileImage")->from('users')->where('id', $record['userId'])->get()->row_array();
        $record['uploadBy'] = $resData['username'];
        $record['profileImage'] = "http:...com/profileImage/".$resData['profileImage'];

        $Mydata[] = $record;
    }
}

Answer 2

在你的请求中（我的意思是选择videos.user_id as userId）在group_by ligne中你使userId通过traitement来进行分组。您的userId别名不知道可以对其进行任何处理的列名称。

用于通过ligne将您的userId替换为您组中的videos.user_id。

您的代码将像这样为您工作

 $this->db->select("videos.user_id as userId");
    $this->db->limit('10', $document['offset']);
    $this->db->group_by('videos.user_id');
    $this->db->order_by('id','desc');

    $recentUploads = $this->db->get('videos')->result_array();
    if (!empty($recentUploads)) 
    {
        foreach ($recentUploads as $record) 
        {
            $totalPostMedia = $obj->totalPostMedia($record);
            $record['totalPostMedia'] = $totalPostMedia;

            $resData = $this->db->select("username, profileImage")->from('users')->where('id', $record['userId'])->get()->row_array();
            $record['uploadBy'] = $resData['username'];
            $record['profileImage'] = "http:...com/profileImage/".$resData['profileImage'];

            $Mydata[] = $record;
        }
    }

Answer 3

使用 max(id)

如$this->db->select("videos.user_id as userId, max(id) ”））；

所以您可以尝试：

    $this->db->select("videos.user_id as userId, max(id)");
    $this->db->limit('10', $document['offset']);
    $this->db->group_by('userId');
    $this->db->order_by('id','desc');

    $recentUploads = $this->db->get('videos')->result_array();
    if (!empty($recentUploads)) 
    {
        foreach ($recentUploads as $record) 
        {
            $totalPostMedia = $obj->totalPostMedia($record);
            $record['totalPostMedia'] = $totalPostMedia;

            $resData = $this->db->select("username, profileImage")->from('users')->where('id', $record['userId'])->get()->row_array();
            $record['uploadBy'] = $resData['username'];
            $record['profileImage'] = "http:...com/profileImage/".$resData['profileImage'];

            $Mydata[] = $record;
        }
    }

https://stackoverflow.com/a/14770936/1815624

Codeigniter group_by无法正常工作

3 个答案: