Question

我有这个mysql选择查询：

SELECT s.* 
FROM campaign_statistic AS s INNER JOIN campaign AS c ON s.campaign_id = c.campaign_id 
WHERE c.campaign_id = 51 
AND date(s.created_date) BETWEEN date(c.start_date) AND date(c.end_date)

得到这个结果：

id  campaign_id     instagram_id    media_id                        has_tag     comments_count  likes_count     created_date            status
**  ***********     ************    ****************************    ********    *************   ***********     *******************     ******
1   51              1230544324      957801995790641919_1230544324   together    1               16              2015-11-01 13:10:29     1
2   51              1230544324      957799073015065299_1230544324   together    2               11              2015-11-01 13:10:29     1
3   51              1230544324      957790310736521811_1230544324   together    5               20              2015-11-01 13:10:29     1
4   51              1230544324      957801995790641919_1230544324   together    1               16              2015-11-02 13:10:29     1
5   51              1230544324      957799073015065299_1230544324   together    2               11              2015-11-02 13:10:29     1
6   51              1230544324      957790310736521811_1230544324   together    5               20              2015-11-02 13:10:29     1
7   51              1230544324      957801995790641919_1230544324   together    1               16              2015-11-03 13:10:29     1
8   51              1230544324      957799073015065299_1230544324   together    2               11              2015-11-03 13:10:29     1
9   51              1230544324      957790310736521811_1230544324   together    5               20              2015-11-03 13:10:29     1

但我想尝试只获取created_date从上面的结果中最大的记录，而最大的created_date是2015-11-03。

我需要这个结果：

id  campaign_id     instagram_id    media_id                        has_tag     comments_count  likes_count     created_date            status
**  ***********     ************    ****************************    ********    *************   ***********     *******************     ******
7   51              1230544324      957801995790641919_1230544324   together    1               16              2015-11-03 13:10:29     1
8   51              1230544324      957799073015065299_1230544324   together    2               11              2015-11-03 13:10:29     1
9   51              1230544324      957790310736521811_1230544324   together    5               20              2015-11-03 13:10:29     1

有任何想法或建议吗？

感谢。

Answer 1

你可以试试这个：

SELECT s.* 
FROM campaign_statistic AS s INNER JOIN campaign AS c ON s.campaign_id = c.campaign_id 
WHERE c.campaign_id = 51 
AND date(s.created_date) BETWEEN date(c.start_date) AND date(c.end_date)
    AND date(s.created_date) = (
    SELECT date(max(s.created_date)) 
FROM campaign_statistic AS s INNER JOIN campaign AS c ON s.campaign_id = c.campaign_id 
WHERE c.campaign_id = 51 
AND date(s.created_date) BETWEEN date(c.start_date) AND date(c.end_date))

Answer 2

以下是使用not exists获取每created_date个campagin_id

的行的方法

SELECT s.* 
FROM campaign_statistic AS s INNER JOIN campaign AS c ON s.campaign_id = c.campaign_id 
WHERE c.campaign_id = 51 
AND date(s.created_date) BETWEEN date(c.start_date) AND date(c.end_date)
AND NOT EXISTS (
    SELECT 1 FROM campaign_statistic AS s2
    INNER JOIN campaign c2 ON s2.campaign_id = c2.campaign_id
    WHERE s2.campaign_id = s.campaign_id
    AND s2.created_date > s.created_date
)

Answer 3

有一些方法可以使用子查询来执行此操作，但我认为最简单的是使用变量，因为连接和过滤：

SELECT cs.*
FROM (SELECT s.* ,
             (@rn := if(@d = date(s.created_date), @rn,
                        if(@d := date(s.created_date), @rn + 1, @rn + 1)
                       )
             ) rn
      FROM campaign_statistic s INNER JOIN
           campaign c
           ON s.campaign_id = c.campaign_id CROSS JOIN
           (SELECT @d := 0, @rn := 0) params
      WHERE c.campaign_id = 51 AND
            date(s.created_date) BETWEEN date(c.start_date) AND date(c.end_date)
      ORDER BY s.created_date desc
     ) cs
WHERE rn = 1;

变量基本上是dense_rank()列上的created_date。

我建议将WHERE子句写为：

      WHERE s.campaign_id = 51 AND
            s.created_date >= DATE(c.start_date) AND
            s.created_date < DATE_ADD(DATE(c.end_date), interval 1 day)

然后我认为查询可以利用campaign_statistic(campaign_id, created_date)上的索引。

MySQL - 过滤记录哪个日期最大

3 个答案: