Question

我有一个包含数字和日期的表格（每个日期和日期不一定是固定间隔的1个数字）。我希望得到一个数字不在表中的日期计数。

我在哪里：

select * 
from 
(   
    select 
    date from nums 
    where chiffre=1 
    order by date desc 
    limit 2
) as f

我明白了：

date
--------------
2014-09-07
--------------
2014-07-26

基本上，我动态地进行了这个查询：

select * from nums where date between "2014-07-26" and "2014-09-07"

并且第二次浏览整个表格（因为我限制了前两行，但我会比较2和3以及3和4等...）

目标是得到这个：

date                      |   actual_number_of_real_dates_between_two_given_dates
2014-09-07 - 2014-07-26   |        20
2014-04-02 - 2014-02-12   |        13

等...

我该怎么做？感谢。

编辑：

我所拥有的（只是一个例子，日期和“chiffre”更复杂）：

date                      |   chiffre
2014-09-30                |        2
2014-09-29                |        1
2014-09-28                |        2
2014-09-27                |        2
2014-09-26                |        1
2014-09-25                |        2
2014-09-24                |        2

等...

我需要的数字为“1”：

actual_number_of_real_dates_between_two_given_dates
  1
  3

等...

编辑2：

感谢Gordon Linoff

我的更新查询

select count(n.id) as difference
from nums n inner join
     (select min(date) as d1, max(date) as d2
      from (select date from nums where chiffre=1 order by date desc limit 2) d
     ) dd
where n.date between dd.d1 and dd.d2

如何用3测试第2行？ 3等4等...不仅仅是2？我应该使用循环吗？或者我可以不用吗？

Answer 1

这样做你想要的吗？

select count(distinct n.date) as numDates,
       (datediff(dd.d2, dd.d1) + 1) as datesInPeriod,
       (datediff(dd.d2, dd.d1) + 1 - count(distinct n.date)) as missingDates
from nums n cross join
     (select date('2014-07-26') as d1, date('2014-09-07') as d2) d
where n.date between dd.d1 and dd.d2;

编辑：

如果您只想要最后两个日期：

select count(distinct n.date) as numDates,
       (datediff(dd.d2, dd.d1) + 1) as datesInPeriod,
       (datediff(dd.d2, dd.d1) + 1 - count(distinct n.date)) as missingDates
from nums n cross join
     (select min(date) as d1, max(date) as d2
      from (select date from nums order by date desc limit 2) d
     ) dd
where n.date between dd.d1 and dd.d2;

使用子查询结果

1 个答案: