mysql查询按日期获取行数据的最大计数？

Question

我有一个表名称为a_ad_display，并具有以下列

displayId | campaignId | displaytime(date)

1          |    2      | 2012-12-19 12:41:08
2          |    2      | 2012-12-19 01:41:08
3          |    1      | 2012-12-20 10:41:08
4          |    1      | 2012-12-20 02:41:08
5          |    1      | 2012-12-21 12:41:08
6          |    2      | 2012-12-21 01:41:08
7          |    1      | 2012-12-21 12:41:08
8          |    1      | 2012-12-21 02:41:08

现在应该要有多个具有相同CampaignId的条目。现在我想要的是首先获取a_ad_display中具有最高计数的campaignId，对于该CampaignId，我想获取日期内的总数

例如..从上表中，我有1个CampaignId，其行数最高

所以对于1个编号campaignId我想显示这样的记录。

        **Date**     | **countPerDay**
 2012-12-19          |      0
 2012-12-20          |      2
 2012-12-21          |      3

我如何在mysql数据库中实现这一目标...希望任何人都可以指导我...

Answer 1

您可以使用此查询

select 
    count(campaignId) as TCount,
    DATE(displayTime) as `Date`
from a_ad_display
where campaignId = 1
group by DATE(displayTime)

虽然不会显示0。

编辑：

确定这将被修改并获取您的结果。

select
  date(a.displayTime) as `DisplayTime`,
  ifnull(l.TCount,0) as TCount
from a_ad_display as a
  left join (select
           count(campaignId) as TCount,
           displayTime
         from a_ad_display
         where campaignId = 1
         group by DATE(displayTime)) as l
    on date(a.displayTime) = date(l.displayTime)
group by DATE(a.displayTime)

演示版

更多编辑：

select
  date(a.displayTime) as `DisplayTime`,
  ifnull(l.TCount,0) as TCount
from a_ad_display as a
  left join (select
           count(campaignId) as TCount,
           displayTime
         from a_ad_display
         where campaignId = 1
         group by DATE(displayTime)) as l
    on date(a.displayTime) = date(l.displayTime)
group by DATE(a.displayTime)
order by a.displaytime desc limit 5

这样您可以选择最新的5条记录。 如果您想选择最新的广告系列，则可以使用子查询代替1，以查看此查询

select
  date(a.displayTime) as `DisplayTime`,
  ifnull(l.TCount,0) as TCount
from a_ad_display as a
  left join (select
       count(campaignId) as TCount,
       displayTime
     from a_ad_display
     where campaignId = (select  campaignId from a_ad_display group by campaignId order by count(campaignId) desc limit 1)
     group by DATE(displayTime)) as l
    on date(a.displayTime) = date(l.displayTime)
group by DATE(a.displayTime)

编辑：

我已经编辑了查询，它将获取更高的出现率CampaignId并相应地获取结果

演示版

Answer 2

这也将显示0

 select 
       sum(case when campaignId = @inputCompainid then 1 else 0 end) as TCount, 
        DATE(displayTime) as `Date`
    from a_ad_display
    group by DATE(displayTime)

Answer 3

以下查询为您提供每个campaignId的记录列表

select campaignId,date(displaytime) as Date,count(*) as countPerDay from a_ad_display group by campaignId,date(displaytime);

如果您需要特定的campaignId，请使用以下代码：

select campaignId,date(displaytime) as Date,count(*) as countPerDay from a_ad_display group by campaignId,date(displaytime) having campaignId=1;

Answer 4

很想问这个，但是这个查询哪个更好？？

1. 山大先生的回答

EXPLAIN SELECT DATE(a.displayTime) AS `DisplayTime`,IFNULL(l.TCount,0) AS TCount
FROM a_ad_display AS a
LEFT JOIN (SELECT
       COUNT(campaignId) AS TCount,
       displayTime
     FROM a_ad_display
     WHERE campaignId = 1
     GROUP BY DATE(displayTime)) AS l
ON DATE(a.displayTime) = DATE(l.displayTime)
GROUP BY DATE(a.displayTime);


id  select_type  table         type  possible_keys  key  key_len  ref  rows  Extra                                            
1   PRIMARY      <derived2>    ALL                                     2                                                   
1   PRIMARY      a             ALL                                     8     Using temporary; Using filesort               
2   DERIVED      a_ad_display  ALL                                     8     Using where; Using temporary; Using filesort  

2.或使用这个

EXPLAIN SELECT DATE(a_ad_display.`displaytime`) AS `DATE`, 
               COUNT(a.`campaignId`) AS `COUNT Per Day` 
        FROM a_ad_display 
        LEFT JOIN (SELECT `a_ad_display`.`displayId`,
                          `a_ad_display`.`campaignId` 
                   FROM `a_ad_display` 
                   WHERE `a_ad_display`.`campaignId`=1) a 
        ON (`a_ad_display`.`displayId`=a.`displayId`)
        GROUP BY `a_ad_display`.`displaytime`;

id  select_type  table         type  possible_keys  key  key_len  ref  rows  Extra                              
1   PRIMARY      a_ad_display  ALL                                     8     Using temporary; Using filesort  
1   PRIMARY      <derived2>    ALL                                     5                                       
2   DERIVED      a_ad_display  ALL                                     8     Using where                      

谢谢之前和之后：D

编辑最高的CampaignId发生率

SELECT DATE(a_ad_display.`displaytime`) AS `DATE`, COUNT(a.`campaignId`) AS `COUNT Per Day` FROM a_ad_display 
LEFT JOIN (SELECT `a_ad_display`.`displayId`,`a_ad_display`.`campaignId` FROM `a_ad_display`
   INNER  JOIN (SELECT COUNT(`a_ad_display`.`campaignId`) AS `count`, `a_ad_display`.`campaignId` 
        FROM `a_ad_display` 
        GROUP BY `a_ad_display`.`campaignId` 
        ORDER BY `count` DESC 
        LIMIT 1) b ON (a_ad_display.`campaignId`=b.`campaignId`)
   ) a ON (`a_ad_display`.`displayId`=a.`displayId`)
GROUP BY `DATE`;

GROUP BY a_ad_display 。 displaytime ; / *此声明中的错误...，抱歉* /它应该现在可以正常工作...再试一次。 您可以在这里http://sqlfiddle.com/#!2/bc75b/1签入，希望它可以在：D中使用