Question

我试图获取谷歌图表的数据。我想得到每天每小时的总和值。但DISTINCT不适用于GROUP BY。

SELECT DATE_FORMAT(created_at, "%Y-%m-%d %H:00:00") as date,
COUNT(DISTINCT visitor_id) as visitors FROM `visitors`  
WHERE web='example.com' AND created_at BETWEEN '2017-11-02 00:00:00' AND '2017-11-02 23:59:59'

没有GROUP BY的结果将是。

date                   visitors
---------------------|----------|
2017-11-02 14:00:00  |   2168   |

GROUP BY date的结果将是

date                   visitors
---------------------|----------|
2017-11-02 00:00:00  |    19    | 
2017-11-02 01:00:00  |    16    |
2017-11-02 02:00:00  |    18    |
...                       ...
total will be 2749

我希望达到第二个结果，但是具有唯一值的正确总和

第二个问题是我怎样才能确定几天后我的独特价值不会被分配到另一个日期？

Answer 1

你应该能够用这个计算正确的总和：

SELECT DATE_FORMAT(created_at, "%Y-%m-%d %H:00:00") as date,
COUNT(visitor_id) as visitors

FROM (
  SELECT MIN(created_at) AS created_at, visitor_id
  FROM `visitors`

  WHERE web='example.com'
  AND created_at BETWEEN '2017-11-02 00:00:00' AND '2017-11-02 23:59:59'

  GROUP BY visitor_id
) all_visits

GROUP BY DATE_FORMAT(created_at, "%Y-%m-%d %H:00:00")

MySQL DISTINCT不适用于GROUP BY时间戳

1 个答案: