Question

我想从此表中获取max（date），count（id）和 * look_name for max（date）* ：

id | member_id | look_week | look_name            | is_pinned | date 

1  |   1       |   3       | the improviser       | yes       | 2013-11-19 21:57:04
2  |   1       |   2       | destined for stardom | yes       | 2013-11-19 21:56:00
2  |   1       |   1       | fashinably corporate | no        | 2013-11-19 21:54:00

这是我的疑问： -

$sql="SELECT COUNT(id) as total_pins,MAX(pinned_date) as last_activity_date FROM pin_info WHERE member_id='1' AND is_pinned='yes'";

我把这个数组放到了外面。

//[total_pins] => 2
//[last_activity_date] => 2013-11-19 21:57:04
//[lookname_for_last_date] => i am stuck at this?

如何操作此查询以便我可以在此数组中获取 look_name for max（date）？

Answer 1

第1步：首先，您必须选择MAX（pinned_date）。我假设这是针对一个特定成员而且is_pinned ='yes'

第2步：然后，您必须选择其中pinned_date等于上面找到的最大日期的look_name。您可以通过在步骤2中进行步骤1和内部查询来完成此操作

第3步：最后，来自第2步的查询将作为主查询中的第3列

    SELECT COUNT(*) as total_pins, MAX(pinned_date) as last_activity_date,
     (select look_name 
      from pin_info B 
      where A.member_id=B.member_id and A.is_pinned=B.is_pinned
        and pinned_date in (
         select max(pinned_date) 
         from pin_info C 
         where B.member_id=C.member_id and B.is_pinned=C.is_pinned
        ) AS lookname_for_last_date
     ),
       (
         select max(pinned_date) 
         from pin_info C 
         where A.member_id=C.member_id and A.is_pinned=C.is_pinned
        ) AS CHK_LAST_DATE

    FROM pin_info A
    WHERE member_id='1' 
    AND is_pinned='yes'

要检查或调整它，see this SQL Fiddle here。

大部分都是类似的..这给了我确切的结果。

 $sub_query="SELECT MAX(pinned_date) FROM pin_info WHERE member_id='$member_id' AND is_pinned='yes'";

$sql = "SELECT COUNT(*) as total_pins, MAX(pinned_date) as last_activity_date,(SELECT look_name FROM pin_info WHERE member_id='$member_id' AND pinned_date=($sub_query)) as last_pinned_look FROM pin_info WHERE member_id='$member_id' AND is_pinned='yes'";

Answer 2

我会选择一个子选择：

SELECT COUNT(id) as total_pins, MAX(pinned_date) as last_activity_date,
(SELECT look_name FROM pin_info WHERE pinned_date = (SELECT MAX(pinned_date) FROM look_info)) as lookNameForMaxDate
FROM pin_info WHERE member_id='%s' AND is_pinned='yes'

在where子句中添加什么来获得所需的结果？

2 个答案: