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在下面的示例查询中，我正在提取与关键字匹配的所有文本并按年月拆分结果。我更喜欢搜索“文本”——所有字符串的连接版本，而不是只针对每个带有 WHERE 子句的字段，但 HAVING 不返回任何数据：

SELECT 
date_format(created_date, '%Y-%m') as yr_mo,
count(id),
group_concat(coalesce(title,''),coalesce(story,'') SEPARATOR ' ') as text
from input_form
where dupe = 0 /*and story like '%flood%'*/
group by yr_mo
having text like '%flood%'
order by yr_mo

以下是当我取消注释 /** 和 '%flood%' **/ 之类的故事并删除 HAVING 子句时返回的内容：

yr_mo   count(id)   text
2011-04 2   Floods Roads in my  community one time proved to b...
2011-05 21  THE TRUSTED LADY.   It was during my usual visits ...
2011-06 22  HEAVY RAINFALL On our village we were affected wit...
2011-07 52  FEED THE CHILDREN PROGRAMME(1) The world food prog...
2011-08 29  I was saved and helped to prosperI am one of the v...
2011-09 15  FLOODS In the past three months the country have f...
2011-10 19  FLOODFlood is a very bad disaster at the same time...
2011-11 9   RESPONDING TO DISASASTERUNICEF landed over relief ...
2011-12 3   EARLY PREVENTION OF FLOODShaving sensed the likeli...
2012-01 44  HUNGER STRIKE             In Wataalamu village the...
2012-04 8   THE FALLEN BRIDGEThe Kambu bridge along the Mombas...
2012-05 7   Increasing earth's natural environment awarenessAf...
2012-06 4   A misery solvedRecently 10 people died in my commu...
2012-07 21  Lsot HopesWhen the Agricultural Farmers Society ca...

我试过用 coalesce(story,'') 避免空值，但结果是一样的。

编辑#1：我发现了一个更长更混乱的查询，并为我提供了我想要的：

SELECT 
date_format(created_date, '%Y-%m') as yr_mo,
count(if( ( story like '%hunger%' OR title like '%hunger%' ) and (story_location_city like '%nairobi%' OR story_location_neighborhood like '%nairobi%'),id,null)) as 'hunger',
count(if( ( story like '%poverty%' OR title like '%poverty%' ) and (story_location_city like '%nairobi%' OR story_location_neighborhood like '%nairobi%'),id,null)) as 'poverty',
count(if( ( story like '%school%' OR title like '%school%' ) and (story_location_city like '%nairobi%' OR story_location_neighborhood like '%nairobi%'),id,null)) as 'school',
count(id) as total
from input_form
where dupe = 0
group by yr_mo
order by yr_mo

如果必须，我可以搜索 if() 语句中的每个字段，它会提供特定的结果。没有更有效的方法来做到这一点吗？

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1 回答 1

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GROUP_CONCAT将其输出截断为（默认情况下） 1024 characters，因此该HAVING子句要求字符串flood出现在连接文本的前 1024 个字符内，而该WHERE子句仅要求它出现在input_form.story.

即使不是为了截断，我认为GROUP_CONCAT+HAVING也不会是您真正想要的，因为这将包括具有任何匹配记录的任何月份的所有记录。例如，如果 2012 年 4 月有 20 条记录，但只有 10 条包含，那么+方法将（如果不用于截断）表示 2012 年 4 月有 20 条匹配记录，并将包含所有这些记录中的文本。floodGROUP_CONCATHAVING

于 2012-07-13T20:55:45.760 回答