Question

我有这些数据，我希望对字段USAGE_FLAG求和，但在它降为0时移动或移动到新ID，保持数据集按SU_ID和WEEK排序：< / p>

SU_ID   WEEK    USAGE_FLAG
100        1    0
100        2    7
100        3    7
100        4    0
101        1    0
101        2    7
101        3    0
101        4    7
102        1    7
102        2    7
102        3    7
102        4    0

所以我想创建这个表：

SU_ID   WEEK    USAGE_FLAG    SUM
100        1    0             0
100        2    7             7
100        3    7             14
100        4    0             0
101        1    0             0
101        2    7             7
101        3    0             0
101        4    7             7
102        1    7             7
102        2    7             14
102        3    7             21
102        4    0             0

我使用MSUM()尝试了GROUP BY功能，但它不会保留上面我想要的顺序。它将7和周数字组合在一起，这是我不想要的。

任何人都知道这是否可行？我正在使用teradata

Answer 1

在标准SQL中，可以使用窗口函数来完成运行总和：

select su_id,
       week,
       usage_flag, 
       sum(usage_flag) over (partition by su_id order by week) as running_sum
from the_table;

我知道Teradata支持窗口函数，我只是不知道它是否也支持窗口定义中的顺序。

重置总和有点复杂。你首先需要创建每次usage_flag变为0时都会改变的“组ID”。以下在PostgreSQL中有效，我不知道这是否也适用于Teradata：

select su_id,
       week,
       usage_flag,
       sum(usage_flag) over (partition by su_id, group_nr order by week) as running_sum
from (
  select t1.*,
         sum(group_flag) over (partition by su_id order by week) as group_nr
  from (
      select *,
             case
                when usage_flag = 0 then 1
                else 0
              end as group_flag
      from the_table
  ) t1
) t2
order by su_id, week;

Answer 2

尝试下面的代码，使用RESET功能它工作正常。

select su_id,
       week,
       usage_flag, 
       SUM(usage_flag) OVER (
        PARTITION BY su_id
        ORDER BY week
        RESET WHEN usage_flag < /* preceding row */ SUM(usage_flag) OVER (
             PARTITION BY su_id ORDER BY week
             ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING)
        ROWS UNBOUNDED PRECEDING
   )
from emp_su;

Answer 3

请尝试以下SQL：

select su_id,
       week,
       usage_flag, 
       SUM(usage_flag) OVER (PARTITION BY su_id ORDER BY week
        RESET WHEN usage_flag = 0 
        ROWS UNBOUNDED PRECEDING
   )
from emp_su;

这里 RESET WHEN usage_flag = 0 会在sum_using_flag减少为0时重置总和

如何根据teradata SQL中的条件计算移动总和？

3 个答案: