如何使用 Netezza 计算连续日期

Question

我需要计算连续的天数才能定义我的同类群组。我有一个 table 看起来像：

pat_id         admin_date
----------------------------
1              3/10/2019
1              3/11/2019
1              3/23/2019
1              3/24/2019
1              3/25/2019
2              12/26/2017
2              2/27/2019
2              3/16/2019
2              3/17/2019

我想要这样的输出：

pat_id         admin_date      consecutive
--------------------------------------------
1              3/10/2019            1
1              3/11/2019            2
1              3/23/2019            1
1              3/24/2019            2
1              3/25/2019            3
2              12/26/2017           1
2              2/27/2019            1
2              3/16/2019            1
2              3/17/2019            2

这样我就可以使用这些连续天数值（每个 pat_id）来筛选我的同类群组。我看过一些建议使用 DateDiff/DateAdd 和 row_number 的帖子，例如：

datediff(day, -row_number() over (partition by mrn order by admin_date), admin_date)

但是 datediff/dateadd 函数在 Netezza 上不起作用...

到目前为止我最接近的是：

select row_number() over (partition by mrn order by administration_date) as consecutive

无法识别日期之间的间隔和 return 这样的输出：

pat_id         admin_date      consecutive
--------------------------------------------
1              3/10/2019            1
1              3/11/2019            2
1              3/23/2019            3
1              3/24/2019            4
1              3/25/2019            5
2              12/26/2017           1
2              2/27/2019            2
2              3/16/2019            3
2              3/17/2019            4

有谁知道如何解决这个问题？

Answer 1

使用lag() 查看组的起始位置和累计总和来定义组。剩下的只是 row_number():

select t.*,
       row_number() over (partition by pat_id, grp order by admin_date) as consecutive
from (select t.*,
             sum( case when prev_ad = admin_date - interval '1 day' then 0 else 1 end) over
                 (partition by pat_id order by admin_date) as grp
      from (select t.*, 
                   lag(admin_date) over (partition by pat_id order by admin_date) as prev_ad
            from t
           ) t
     )t ;

如何使用 Netezza 计算连续日期

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