下一步使用解析函数

Question

对于队列分析的需要，我试图获得每个客户的下一步行动(取消订阅，升级，降级…)

我有一个包含以下数据的月快照:

customer | month      | last_action   | last_action_date
1          01-01-2012   subscription    01-01-2012
1          02-01-2012   subscription    01-01-2012
1          03-01-2012   subscription    01-01-2012
1          04-01-2012   downgrade       04-01-2012
1          05-01-2012   downgrade       04-01-2012
1          06-01-2012   downgrade       04-01-2012
1          07-01-2012   unsubscription  07-01-2012

正如你所看到的，这个动作只在它完成的月份是已知的，在2012-01-01这个月，我们还不知道客户在2012-01-01被降级了，所以我们不能分析他的使用行为相对于他的降级月份。退订也是一样。

需要的数据集如下:

customer | month      | downgrade_date   | unsubscription_date
1          01-01-2012   04-01-2012         07-01-2012
1          02-01-2012   04-01-2012         07-01-2012
1          03-01-2012   04-01-2012         07-01-2012
1          04-01-2012   12-31-9999         07-01-2012
1          05-01-2012   12-31-9999         07-01-2012
1          06-01-2012   12-31-9999         07-01-2012
1          07-01-2012   12-31-9999         07-01-2012

我可以通过last_value分析函数轻松获得退订日期，但没有找到获得降级日期的方法。

这是我的SQL查询:

SELECT month_id, 
       customer_id,
       CASE 
         WHEN LAST_VALUE(last_action) OVER (PARTITION BY customer_id ORDER BY month_id RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING) = 'unsubscription' THEN LAST_VALUE(last_action_date) OVER (PARTITION BY customer_id ORDER BY month_id RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)    
         ELSE TO_DATE('99991231', 'yyyymmdd')
       END unsubscription_date
FROM my_table
;

任何获取"下一个"动作日期的方法，如"downgrade_date"。

Answer 1

在oracle 11中，您可以使用lead()和ignore nulls选项:

select customer, MONTH,
       lead(case when last_action = 'downgrade' then last_action_date end ignore nulls) over
                 (partition by customer order by month desc) as downgrade_date,
       lead(case when last_action = 'unsubscription' then last_action_date end ignore nulls) over
                 (partition by customer order by month desc) as downgrade_date,
from my_table t

如果你没有ignore nulls，你可以做类似的min():

select customer, MONTH,
       min(case when last_action = 'downgrade' then last_action_date end) over
                (partition by customer order by month range between current and unbounded following
                ) as downgrade_date,
       min(case when last_action = 'unsubscription' then last_action_date end) over
                (partition by customer order by month range between current and unbounded following
                ) as unsubscription_date
from my_table t