如何将一系列记录转换为 SQL 中该范围之后的记录值？

Question

我正在尝试用正确的记录替换特定日期范围内的一些错误输入记录。但是，我不确定是否有有效的方法。因此，我的问题是如何将（静态）记录范围转换为 SQL 中该范围之后的记录值？您将在下面找到一个示例来阐明我试图实现的目标。

在此示例中，您可以看到客户编号 1 在 25-06-2020 到 29-06-2020 期间属于组编号 0 (None)。从 30-06-2020 到 05-07-2020 此组号从 0 更改为客户编号 1 的 11。此静态期间包含错误记录，应更改为在 06-07-2020 有效的值（组号 == 10）。有办法吗？

Answer 1

我认为 window 函数 first_value() 可以满足您的要求：

select 
    date,
    customer_number,
    first_value(group_number) over(partition by customer_number order by date) group_number,
    first_value(role)         over(partition by customer_number order by date) role
from mytable

Answer 2

如果我理解正确，您可以使用 window 函数获取特定日期的数据，并使用 case 逻辑将其分配到特定日期范围：

select t.*,
       (case when date >= '2020-07-01' and date <= '2020-07-05'
             then max(case when date = '2020-07-06' then group_number end) over (partition by customer_number)
             else group_number
        end) as imputed_group_number,
       (case when date >= '2020-07-01' and date <= '2020-07-05'
             then max(case when date = '2020-07-06' then role end) over (partition by customer_number)
             else role
        end) as imputed_role
from t;

如果要更新值，可以使用 JOIN:

update t
    set group_number = tt.group_number,
        role = tt.role
    from tt
    where tt.customer_number = t.customer_number and tt.date = '2020-07-06'

Answer 3

您可以按照以下示例进行操作。在这里，我选择了以下条件：如果 role='Leader' 它是一个坏记录，因此您将应用下一个可用的 group_number --> 在 group_number1 列和 role1.

我在 excel 示例中使用了较小的行子集。

  select date1
        ,customer_number
        ,group_number
        ,case when role='Leader' then 
                  (select t1.group_number
                     from t t1
                    where t1.date1>t.date1
                      and t1.role<>'Leader'
                   order by t1.date1 asc
                   limit 1
                  ) 
             else group_number 
         end as group_number1
        ,role
       ,case when role='Leader' then 
                  (select t1.role
                     from t t1
                    where t1.date1>t.date1
                      and t1.role<>'Leader'
                   order by t1.date1 asc
                   limit 1
                  ) 
             else role 
         end as role1
   from t
order by 1   

+------------+-----------------+--------------+---------------+--------+--------+
|   DATE1    | CUSTOMER_NUMBER | GROUP_NUMBER | GROUP_NUMBER1 |  ROLE  | ROLE1  |
+------------+-----------------+--------------+---------------+--------+--------+
| 2020-06-25 |               1 |            0 |             0 | None   | None   |
| 2020-06-26 |               1 |            0 |             0 | None   | None   |
| 2020-06-27 |               1 |            0 |             0 | None   | None   |
| 2020-06-28 |               1 |            0 |             0 | None   | None   |
| 2020-06-29 |               1 |            0 |             0 | None   | None   |
| 2020-06-30 |               1 |           11 |            10 | Leader | Member |
| 2020-07-01 |               1 |           11 |            10 | Leader | Member |
| 2020-07-06 |               1 |           10 |            10 | Member | Member |
+------------+-----------------+--------------+---------------+--------+--------+

db fiddle link https://dbfiddle.uk/?rdbms=db2_11.1&fiddle=c95d12ced067c1df94947848b5a94c14

如何将一系列记录转换为 SQL 中该范围之后的记录值？

How to transform a range of records to the values of the record after that range in SQL?

sql

window-functions

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