Question

我有2个表，我想在我的网站列表中显示所有用户，并从表tbl_login_details中显示他的上次登录详细信息，但获得该用户的上次登录详细信息

1-从表中显示所有用户-tbl_user

2-为所有用户显示LAST登录，因此tbl_login_details的数据必须是ORDER然后采用LIMT

---------tbl_user-------
id    user_id   user_name 
1      5         mohammed
2      7          ahmed  

-------------tbl_login_details----------

  id       user_id    last_activity
  1         7          2016-5-2
  2         7          2017-4-2
  3         7          20-17-8-4

我的工作是

$this->db->select('m.*,u.*'); 
$this->db->from('tbl_user m');
//$this->db->where("m.user_id", $id);
$this->db->join('tbl_login_details u ', 'u.user_id = m.user_id');
$where = 'm.user_id = u.user_id OR u.user_id = m.user_id  OR m.user_id=" "  ORDER  last_activity';
$where = $this->db->order_by("last_activity", "desc");
$this->db->where($where);
// $this->db->limit('1'); 
$this->db->group_by('m.user_id');// add group_by
$query = $this->db->get();
return $query->result();

Answer 1

使用最大聚合找到上一个活动：

select userid, max(last_activity)
from tbl_user a inner join tbl_login_details b on a.userid=b.userid

Answer 2

您是否尝试从每个用户那里获取最新的详细信息登录信息，如果可以，则可以使用ORDER DESC AND LIMIT 1

创建查询以首先显示tbl_user

SELECT * FROM tbl_user ORDER BY id ASC

然后您可以创建查询以获取上次用户登录

SELECT * FROM tbl_login_details WHERE user_id = 7 ORDER BY id DESC LIMIT 1

您可以使用模式弹出窗口进行显示详细信息登录。

还是您尝试这样显示？

id    user_id   user_name  last_activity
1      5         mohammed   20-17-8-4
2      7          ahmed     20-17-8-4

Answer 3

可能您正在搜索关注

SELECT user_id, user_name, (SELECT last_activity FROM tbl_login_details WHERE tbl_login_details.user_id = tbl_user.user_id  ORDER BY last_activity DESC LIMIT 1) as last_activity FROM tbl_user

更新的代码。搜索如何在活动记录中编写此子查询。或仅使用自定义查询，例如$ query = $ this-> db-> query（“ YOUR QUERY”）;

Answer 4

帮助CI最大聚合以查找上一个活动：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\timregan\source\MentalHealth\code\preprocessing\feat_transform.py", line 171, in filter_anevexp
    anevexp_df = anevexp_df[anevexp_df["user_id"].isin(df)].copy()
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\frame.py", line 2682, in __getitem__
    return self._getitem_array(key)
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\frame.py", line 2724, in _getitem_array
    return self._take(indexer, axis=0)
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\generic.py", line 2789, in _take
    verify=True)
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\internals.py", line 4539, in take
    axis=axis, allow_dups=True)
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\internals.py", line 4425, in reindex_indexer
    for blk in self.blocks]
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\internals.py", line 4425, in <listcomp>
    for blk in self.blocks]
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\internals.py", line 1258, in take_nd
    allow_fill=True, fill_value=fill_value)
  File "C:\Users\timregan\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\algorithms.py", line 1655, in take_nd
    out = np.empty(out_shape, dtype=dtype)
MemoryError

Answer 5

这是获取该代码的简单SQL代码。您可以通过CodeIgniter的方式来实现：在CodeIgniter中实现此SQL。

SELECT tbl_user.user_id, tbl_user.user_name, tbl_login_details.user_id, tbl_login_details.last_activity FROM tbl_user, tbl_login_details WHERE tbl_user.user_id = tbl_login_details.user_id ORDER BY tbl_login_details.last_activity DESC

Answer 6

希望这可以为您提供帮助

SELECT u.id,u.user_id,u.user_name,MAX(l.last_activity) AS last_activity
FROM tbl_user u
LEFT JOIN tbl_login_details l ON(u.user_id=l.user_id)
GROUP BY u.user_id

在codeigniter自定义查询生成器上

$query = $this->db->query("SELECT u.id,u.user_id,u.user_name,MAX(l.last_activity) AS last_activity FROM tbl_user u LEFT JOIN tbl_login_details l ON(u.user_id=l.user_id) GROUP BY u.user_id");

foreach ($query->result() as $row)
{
        echo $row->id;
        echo $row->user_id;
        echo $row->user_name;
        echo $row->last_activity ;
}

SQL |从2个条件表中查询

6 个答案: