从 TIMESTAMP 字段 MYSQL 创建按日期和小时细分

Question

我正在尝试创建一个查询，该查询按日期和小时提供ids 的细分，其中空白结果显示为零。

到目前为止，这是 MYSQL 查询：

SELECT DATE(received),
  CONCAT(hourly.hour, ':00 - ', hourly.hour+1, ':00') AS Hours,  
  COALESCE(COUNT(id),0) AS "Leads"
FROM hourly
LEFT JOIN digital_lead ON hourly.hour=hour(digital_lead.received)
WHERE 
  digital_lead.received>=DATE_SUB('2014-11-01', INTERVAL 24 HOUR) AND
  digital_lead.received<=DATE_SUB('2014-11-26', INTERVAL 24 HOUR) 
GROUP BY DATE(received), hourly.hour
ORDER BY DATE(received)

我有一个从 0 到 23 的整数表，组成了 hourly 表。

目前，此查询仅显示结果存在的时间段 - 如下所示：

DATE(received)       Hours  Leads
2014-11-12           11:00 - 12:00  23
2014-11-12           12:00 - 13:00  19
2014-11-12           13:00 - 14:00  18
2014-11-12           14:00 - 15:00  17
2014-11-12           15:00 - 16:00  23
2014-11-12           16:00 - 17:00  13
2014-11-12           17:00 - 18:00  17

查询应该显示来自00:00 - 11:00 的时间段的零结果，而不是在查询结果中遗漏它们。它似乎忽略了COALESCE 函数，我尝试用IFNULL(COUNT(id), 0) 替换它，没有区别。

我已经尝试了这个问题/答案中的解决方案 - STACKOVERFLOW LINK

但是，这对我不起作用。

有什么建议吗？

编辑

这里是 SQL FIDDLE 了解更多详情

Answer 1

好的，这需要一些时间。这是我能想到的最好的办法。可能有更好的方法来做到这一点，但加入时缺少日期或时间总是很复杂。我已经给出了与缺少日期相关的few answers，但这是完全不同的。

因此，我使用相同的想法在查询中进行了一些更改以检索数据，如下所示

select
t1.date_received,
t1.Hours,
COALESCE(t2.`Leads`,0) as `Leads`
from
(
  select
  distinct DATE(received) as date_received,
  concat (DATE(received),'-',h.hour) as date_hour,
  CONCAT(h.hour, ':00 - ', h.hour+1, ':00') AS Hours 
  from digital_lead
  cross join (select hour from hourly)h
)t1
left join
(
  SELECT DATE(received) as date_received,
  concat (DATE(received),'-',hour) as date_hour,
  CONCAT(hourly.hour, ':00 - ', hourly.hour+1, ':00') AS Hours,  
  COALESCE(COUNT(id),0) AS "Leads"
  FROM hourly
  LEFT JOIN digital_lead ON hourly.hour=hour(digital_lead.received)
  and digital_lead.received>=DATE_SUB('2014-11-01', INTERVAL 24 HOUR)
  and digital_lead.received<=DATE_SUB('2014-11-26', INTERVAL 24 HOUR) 
  GROUP BY DATE(received), hourly.hour
)t2
on t1.date_hour = t2.date_hour
order by t1.date_received,
cast(substring_index(t1.Hours,':',1) as unsigned)

FIDDLE