将连续的日期有效期合并在一起

将连续的日期有效期合并在一起

这是一个孤岛问题。有多种方法可以解决此问题。这使用

lead

和

lag

分析功能：

select distinct product,  case when start_date is null then lag(start_date)    over (partition by product order by rn) else start_date end as start_date,  case when end_date is null then lead(end_date)    over (partition by product order by rn) else end_date end as end_datefrom (  select product, start_date, end_date, rn  from (    select t.product,      case when lag(end_date)          over (partition by product order by start_date) is null        or lag(end_date)          over (partition by product order by start_date) != start_date - 1        then start_date end as start_date,      case when lead(start_date)          over (partition by product order by start_date) is null        or lead(start_date)          over (partition by product order by start_date) != end_date + 1        then end_date end as end_date,      row_number() over (partition by product order by start_date) as rn    from t  )  where start_date is not null or end_date is not null)order by start_date, product;PRODUCT START_DATE END_DATE------- ---------- ---------A       01-JUL-13  30-SEP-13 B       01-OCT-13  30-NOV-13 A       01-DEC-13  31-MAR-14

SQL小提琴

最里面的查询查看产品的前后记录，并且仅在记录不连续时才保留开始和/或结束时间：

select t.product,  case when lag(end_date)      over (partition by product order by start_date) is null    or lag(end_date)      over (partition by product order by start_date) != start_date - 1    then start_date end as start_date,  case when lead(start_date)      over (partition by product order by start_date) is null    or lead(start_date)      over (partition by product order by start_date) != end_date + 1    then end_date end as end_datefrom t;PRODUCT START_DATE END_DATE------- ---------- ---------A       01-JUL-13 A      A       30-SEP-13 A       01-DEC-13 A      A      A       31-MAR-14 B       01-OCT-13 B       30-NOV-13

select的下一个级别将删除那些处于中期的日期，其中两个日期都被内部查询所遮盖，从而得到：

PRODUCT START_DATE END_DATE------- ---------- ---------A       01-JUL-13 A       30-SEP-13 A       01-DEC-13 A       31-MAR-14 B       01-OCT-13 B       30-NOV-13

然后，外部查询会折叠那些相邻的对；我使用了创建重复项，然后使用消除重复项的简单

distinct

方法，但是您可以通过其他方式进行 *** 作，例如将两个值都放入一对行中，并将两个值都保留为另一个空值，然后用另一个值消除它们选择层，但我认为在这里完全可以。

如果您的实际用例有时间，而不仅仅是日期，那么您需要在内部查询中调整比较；而不是+/-
1，可能是1秒的间隔，或者如果您愿意，则是1/86400，但取决于值的精度。