在SQL中检测和合并日期范围的连续重叠

问题描述

我需要检测并合并表中的重叠日期范围，但仅在连续的行中，不成功的重叠将被忽略。

CREATE TABLE konto (konto_nummer     INTEGER,start_datum DATE,end_datum DATE); 
INSERT INTO konto VALUES (1,'2020-01-01 00:00:00.000000','2020-01-10 00:00:00.000000');
INSERT INTO konto VALUES (1,'2020-01-12 00:00:00.000000','2020-01-20 00:00:00.000000');
INSERT INTO konto VALUES (2,'2020-01-10 00:00:00.000000');
INSERT INTO konto VALUES (2,'2020-01-05 00:00:00.000000','2020-01-15 00:00:00.000000','2020-01-25 00:00:00.000000');
INSERT INTO konto VALUES (2,'2020-02-05 00:00:00.000000','2020-02-20 00:00:00.000000');
INSERT INTO konto VALUES (3,'2020-01-25 00:00:00.000000');
INSERT INTO konto VALUES (4,'2020-04-01 00:00:00.000000','2020-04-10 00:00:00.000000');
INSERT INTO konto VALUES (4,'2020-04-05 00:00:00.000000','2020-04-15 00:00:00.000000');
INSERT INTO konto VALUES (4,'2020-04-16 00:00:00.000000','2020-04-25 00:00:00.000000');
INSERT INTO konto VALUES (4,'2020-04-20 00:00:00.000000','2020-04-30 00:00:00.000000');

相同颜色的行具有连续的重叠。

我尝试了以下

    SELECT
    ROW_NUMBER () OVER (ORDER BY konto_nummer,start_datum,end_datum) AS RN,konto_nummer,end_datum,MAX(end_datum) OVER (PARTITION BY konto_nummer ORDER BY start_datum,end_datum ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) AS Previousend_datum
   FROM konto;

但是它也结合了非连续的重叠。

解决方法

差距和离岛有多个步骤。

首先，标记差距

with mark as (
  select *,lag(end_datum) over w
           not between start_datum and end_datum as island
    from konto
  window w as (partition by konto_nummer
                   order by start_datum,end_datum)
),

然后，编号岛屿

 grps as (
  select *,sum(coalesce(island,true)::int) over w as grpnum 
    from mark
  window w as (partition by konto_nummer
                   order by start_datum,end_datum)
)

然后按组汇总

select konto_nummer,min(start_datum) as start_datum,max(end_datum) as end_datum
  from grps
 group by konto_nummer,grpnum
 order by 1,2,3;

Working fiddle here.

,

当重叠可以是任意的时，我更喜欢使用累积最大值来找到它们，而不是lag()。在这样的情况下可以正常工作：

A ------- B -------- B --------------C-C-------A

这是：

select konto_nummer,min(start_datum),max(end_datum)
from (select k.*,count(*) filter (where prev_end_datum is null or prev_end_datum < start_datum) over
                (partition by konto_nummer order by start_datum) as grp
      from (select k.*,max(end_datum) over (partition by konto_nummer order by start_datum range between unbounded preceding and '1 second' preceding) as prev_end_datum
            from konto k
           ) k
     ) k
group by konto_nummer,grp
order by konto_nummer,min(start_datum);

Here是db 小提琴。