Question

我有两个表，第一个表包含具有唯一ID和关键字的数字，第二个表包含通过唯一ID（在CAMPAIGN列中）链接回第一个表的数字。我想从第一个表中获取每个数字并计算其唯一ID（在CAMPAIGN中）在第二个表中显示的次数（即：每个数字附加了多少个关键字）。

         CAMPAIGNS                                   SUBSCRIBERS
----------------------------------      --------------------------------------
ID    |    NUMBER    |  KEYWORD  |      | ID    |   NUMBER     |   CAMPAIGN  |
----------------------------------      --------------------------------------
1     |  +1222222222 |   pizza   |      |  22   | 555-333-222  |     2       |
----------------------------------      --------------------------------------
2     |  +1222222222 |   burger  |      |  21   | 222-333-222  |     2       |
----------------------------------      --------------------------------------
3     |  +1444444444 |    pie    |      |  33   | 333-111-111  |     1       |
----------------------------------
4     |  +1111111111 |  chicken  |

我需要的结果是：

----------------------------------------
      NUMBER      |  KEYWORD   | COUNT |
----------------------------------------
    +1222222222   |   pizza    |   1   |
----------------------------------------
    +1222222222   |   burger   |   2   |
----------------------------------------
    +1444444444   |    pie     |   0   |
----------------------------------------
    +1111111111   |   chicken  |   0   |

我对JOIN和UNION不太熟悉，所以我一直在试验和阅读文档，但我无法弄清楚如何用它们实现COUNT。

这是我到目前为止所做的，但每当我尝试添加COUNT函数时，我都会收到错误而无法弄明白：

SELECT * FROM `campaigns` LEFT JOIN `subscribers` ON `campaigns`.id = `subscribers`.campaign;

修改发布的查询类型有效，但不包括计数为零的其他广告系列

SELECT c.number,c.id,c.keyword,COUNT(s.id) AS count FROM campaigns AS c LEFT JOIN subscribers AS s ON c.id = s.campaign GROUP BY s.campaign ORDER BY c.id ASC

Answer 1

SELECT c.number,c.keyword,COUNT(s.campaign)  
FROM `campaigns` AS c 
LEFT JOIN `subscribers` AS s ON c.id = s.campaign 
GROUP BY c.id 
ORDER BY c.id ASC

此查询将提供您期望的内容......

Answer 2

SELECT c.number, c.id, c.keyword, ISNULL(s.count,0) AS count
FROM campaigns AS c
LEFT JOIN (
  SELECT Campaign, COUNT(*) AS count
  FROM Subscribers
  GROUP BY Campaign
) AS s
ON c.id = s.Campaign
ORDER BY c.id ASC

Answer 3

SELECT campaigns.number AS number, campaigns.keyword AS keyword, COUNT( subscribers.id ) AS count
FROM  `subscribers` 
LEFT JOIN  `campaigns` ON subscribers.campaign = campaigns.id
GROUP BY campaigns.keyword

是你需要的。唯一不起作用的是显示带有0个订阅者的“馅饼”...我很遗憾没有进入mysql子选择，这就是你需要的。

Answer 4

作为您问题的解决方案，请尝试执行以下sql查询

select c.number,keyword,(select count(id) as count from subscribers
where campaign=c.id) from  campaigns c

从第一个表中选择all，计算第二个表中ID的实例

4 个答案: