mysql - GROUP_CONCAT 有额外的分组吗？

Question

我已经开始编写一个脚本来生成关于特定文章被调用的频率和时间的统计信息

SELECT `title`, `page_id`, COUNT(*) AS `total`, 
GROUP_CONCAT(DISTINCT `date_created` 
             ORDER BY `date_created` SEPARATOR ',') dates 
FROM `statistics` 
WHERE `supplier_id` = '27' 
GROUP BY `title` 
ORDER BY `title`;

产生

[0] => Array
        (
            [0] => Array
                (
                    [total] => 3
                    [dates] => 2011-04-26,2011-04-27
                )

            [statistics] => Array
                (
                    [title] => Title 2
                    [page_id] => 2
                )  
        )

[1] => Array
        (
            [0] => Array
                (
                    [total] => 6
                    [dates] => 2011-04-26,2011-04-27,2011-04-28
                )

            [statistics] => Array
                (
                    [title] => Title 7
                    [page_id] => 7
                )
        )

好东西。但是我如何添加一个类似于日期的字段，它添加了按 date_created 分组的 id 的分割，从而创建如下内容:

[2] => Array
    (
        [0] => Array
            (
                [total] => 6
                [dates] => 2011-04-26,2011-04-27,2011-04-28
                [total_by_date] => 2,1,3
            )

        [statistics] => Array
            (
                [title] => Title 7
                [page_id] => 7
            )
)

我想按照这些行添加一个额外的 GROUP BY:

GROUP_CONCAT(DISTINCT COUNT(*) AS `total_by_date` 
             GROUP BY `date_created` ORDER BY `date_created` SEPARATOR ',')

但它不起作用，我该如何解决？

转储:

CREATE TABLE `statistics` (
  `id` int(11) NOT NULL auto_increment,
  `pagetype` varchar(50) character set utf8 collate utf8_unicode_ci NOT NULL,
  `supplier_id` int(11) NOT NULL,
  `page_id` int(11) default NULL,
  `title` varchar(255) character set utf8 collate utf8_unicode_ci NOT NULL,
  `date_created` date NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=920 ;

-- 
-- Dumping data for table `statistics`
-- 

INSERT INTO `statistics` (`id`, `pagetype`, `supplier_id`, `page_id`, `title`, `date_created`) VALUES 
(1, 'newsarticle', 27, 2751, 'Title 1', '2011-04-26'),
(2, 'newsarticle', 27, 2751, 'Title 1', '2011-04-26'),
(3, 'newsarticle', 27, 2751, 'Title 1', '2011-04-27'),
(4, 'newsarticle', 27, 462009, 'Title 2', '2011-04-26'),
(5, 'newsarticle', 27, 462009, 'Title 2', '2011-04-26'),
(6, 'newsarticle', 27, 462009, 'Title 2', '2011-04-27'),
(7, 'newsarticle', 27, 462009, 'Title 2', '2011-04-27'),
(8, 'newsarticle', 27, 462009, 'Title 2', '2011-04-27'),
(9, 'newsarticle', 27, 462009, 'Title 2', '2011-04-28'),
(10, 'newsarticle', 27, 46200, 'Title 3', '2011-04-26'),
(11, 'newsarticle', 27, 46200, 'Title 3', '2011-04-26'),
(12, 'newsarticle', 27, 46200, 'Title 3', '2011-04-26'),
(13, 'newsarticle', 27, 46200, 'Title 3', '2011-04-26'),
(14, 'newsarticle', 27, 46200, 'Title 3', '2011-04-26');

Answer 1

不能 100% 确定这会奏效，但这是一个开始:

在子查询中执行第二个 GROUP_CONCAT。

SELECT title
  , s1.page_id
  , s2.total_by_date
  , GROUP_CONCAT(DISTINCT s1.date_created
                 ORDER BY s1.date_created SEPARATOR ',') as dates  
FROM statistics s1
INNER JOIN  
  (SELECT page_id
     ,GROUP_CONCAT(/*DISTINCT*/ gc.cnt
     ORDER BY gc.date_created SEPARATOR ',') AS total_by_date
   FROM 
   (
      SELECT count(*) as cnt
        ,date_created
      FROM statistics
      WHERE supplier_id = '27'
      GROUP BY date_created
   ) gc
   GROUP BY gc.date_created
  ) s2 ON (s1.page_id = s2.page_id)      
WHERE supplier_id = '27'  
GROUP BY title  
ORDER BY title; 

使用 distinct count(*) 会隐藏具有相同计数的项目，我认为这不是您想要的，所以我以注释形式将其放入。
顺便说一句，这里不需要 ORDER BY title，因为 GROUP BY 已经按标题排序。