问根据记录之间经过的时间(即行)重新计算开始日期和结束日期。

EN

create table t(CUSTOMERID int, STARTDATE date, ENDDATE date);
insert into t(CUSTOMERID , STARTDATE , ENDDATE )
values
(1, '2021-07-02', '2021-07-14'),
(1, '2021-07-19', '2021-07-27'),
(2, '2018-11-12', '2018-11-16'),
(2, '2018-11-17', '2018-11-19'),
(2, '2018-11-19', '2018-11-25'),
(2, '2019-01-10', '2019-01-15');


select CUSTOMERID , STARTDATE , ENDDATE,
 max(sdate) over(partition by CUSTOMERID order by STARTDATE ) as NewStartDate,
 min(edate) over(partition by CUSTOMERID order by STARTDATE rows between current row and unbounded following) as NewEndDate
from
(
select *, 
 case when STARTDATE <= lag(dateadd(day, 1, ENDDATE)) over(partition by CUSTOMERID order by STARTDATE ) then null 
      else STARTDATE 
 end as sdate,
 case when ENDDATE>= lead(dateadd(day, -1, STARTDATE )) over(partition by CUSTOMERID order by STARTDATE ) then null 
      else ENDDATE
 end as edate
from t
) as t
order by STARTDATE ;