php – Mysql GROUP BY概述投票系统

我希望user_id 2概述其他用户在其帐户中执行的最后一个操作

>投票
>投票否决
>确认
>不肯定

每次用户执行操作时,在右列中添加一行1.空白元素填充0.

user是投票人,user_id是投票的人

| id | user | user_id | up | down | confirm | unconfirm |    date    |
+----+------+---------+----+------+---------+-----------+------------+
| 1  |  1   |    2    | 1  |      |         |           | 2014-11-03 |
| 2  |  1   |    2    | 1  |      |         |           | 2014-11-03 |
| 3  |  1   |    2    |    |  1   |         |           | 2014-11-03 |
| 4  |  1   |    2    |    |  1   |         |           | 2014-11-03 |
| 5  |  1   |    2    |    |  1   |         |           | 2014-11-03 |
| 6  |  1   |    2    | 1  |      |         |           | 2014-11-03 |
| 7  |  1   |    2    |    |      |    1    |           | 2014-11-03 |
| 8  |  1   |    2    |    |      |         |     1     | 2014-11-03 |
| 9  |  1   |    2    |    |      |    1    |           | 2014-11-03 | //THIS
| 10 |  1   |    2    | 1  |      |         |           | 2014-11-03 | // THIS
| 11 |  3   |    2    |    |  1   |         |           | 2014-11-03 |
| 12 |  3   |    2    | 1  |      |         |           | 2014-11-03 | //THIS
| 13 |  3   |    2    |    |      |    1    |           | 2014-11-03 | // THIS
+----+------+---------+----+------+---------+-----------+------------+

输出：最后一次上或下,最后一次确认或取消确认每个用户
– 用户3确认,
– 用户3 Up,
– 用户1,
– 用户1确认.

SELECT * FROM table WHERE user_id = 2 GROUP BY .. ORDER BY id DESC

if($data['up'] == '1')
{
 echo "You have been Voted up ... You've earned.."; 
}

else if($data['down'] == '1')
{
 echo "You have been Voted down ... Now you need to.."; 
}

...

解决方法:

要获取对用户执行的最新操作,您可以使用该user_id拉出所有行,按日期降序排序,并限制为1.尝试以下操作：

SELECT *
FROM myTable
WHERE user_id = 2
ORDER BY date DESC
LIMIT 1;

另一个注意事项

如果我可以在这里评论你的表格设计,我真的认为你可以将各种动作放入他们自己的表格中,并在你的表格中有一个action_id列.换句话说,它看起来像这样：

action_values：

| id |   action  |
+----+-----------+
| 1  | up        |
| 2  | down      |
| 3  | confirm   |
| 4  | unconfirm |

动作：

| id | user | user_id | actionID |    date    |
+----+------+---------+----------+------------+
| 1  |  1   |    2    |     1    | 2014-11-03 |
| 2  |  1   |    2    |     1    | 2014-11-03 |
| 3  |  1   |    2    |     2    | 2014-11-03 |
| 4  |  1   |    2    |     2    | 2014-11-03 |
| 5  |  1   |    2    |     2    | 2014-11-03 |
| 6  |  1   |    2    |     1    | 2014-11-03 |
| 7  |  1   |    2    |     3    | 2014-11-03 |
| 8  |  1   |    2    |     4    | 2014-11-03 |
| 9  |  1   |    2    |     3    | 2014-11-03 |
| 10 |  1   |    2    |     1    | 2014-11-03 |
| 11 |  3   |    2    |     2    | 2014-11-03 |
| 12 |  3   |    2    |     1    | 2014-11-03 |
| 13 |  3   |    2    |     3    | 2014-11-03 |

这会使您的查询有点不同,但它肯定会使事情更好地正常化,并有助于避免插入和更新异常.如果您对此感兴趣,请参阅this SQL Fiddle以获取有关查询如何更改的示例.

编辑

关于获取最新动作,请参阅我的答案here.这可能会有所帮助,因为它讨论了从一个小组中获取N个案例,这是您在这里尝试做的事情.您希望从每个组中获取单个最新案例.

所以,我试图在sql fiddle中做到这一点,并尝试了一些试验和错误,但我能够让它工作.不幸的是,我无法找到解决这一问题的方法,但我能够提出这个查询,从每个用户获取最新的或最新的：

SELECT *
FROM myTable m
WHERE(
  SELECT COUNT(*)
  FROM myTable mt
  WHERE mt.user_id = 2
    AND m.user_id = 2
    AND mt.user = m.user
    AND mt.date >= m.date
    AND (mt.up = 1 OR mt.down = 1)
) <= 1
AND (m.up = 1 OR m.down = 1);

简而言之,嵌套部分的作用是获取投票用户2的行,投票用户分组,过滤最大日期,并将结果限制为0或1行.我在这里添加了上下条件,以便它只会在行动向上或向下的情况下拉行.很容易,您可以编写相反的查询来确认/取消确认,并将两者联合起来,如下所示：

(SELECT *
FROM myTable m
WHERE(
  SELECT COUNT(*)
  FROM myTable mt
  WHERE mt.user_id = 2
    AND m.user_id = 2
    AND mt.user = m.user
    AND mt.date >= m.date
    AND (mt.up = 1 OR mt.down = 1)
) <= 1
AND (m.up = 1 OR m.down = 1))
UNION
(SELECT *
FROM myTable m
WHERE(
  SELECT COUNT(*)
  FROM myTable mt
  WHERE mt.user_id = 2
    AND m.user_id = 2
    AND mt.user = m.user
    AND mt.date >= m.date
    AND (mt.confirm = 1 OR mt.confirm = 1)
) <= 1
AND (m.confirm = 1 OR m.confirm = 1));

我正在玩弄如何缩短这个查询,但在这个特定的时刻它是我所拥有的最好的,它是working,所以希望这会让你再次前进.

php – Mysql GROUP BY概述投票系统

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