在SQL中动态比较不同列和行中的日期

Question

我有一组像这样的数据。

数据

ID  Start_dt    End_dt
A   1/1/2010    12/31/2010
A   1/1/2011    12/31/2011
A   6/1/2012    12/31/2012
A   1/1/2014    12/31/2014
A   1/1/2016    10/31/2016
A   1/1/2018    12/31/2018
B   1/1/2016    2/29/2016
B   3/1/2016    10/31/2016
B   1/1/2017    7/31/2017
B   1/1/2019    12/31/9999
C   1/1/2017    12/31/2017
C   1/1/2017    12/31/2018
C   1/1/2019    12/31/9999

我需要创建一个查看每个成员行的查询，将当前的Start_dt与之前的End_dt进行比较。如果差异小于一年，则将这两个记录视为一个连续注册，并返回组合的MIN Start_dt和MAX End_dt，并对每个成员的所有行重复该记录。如果差异> = 1年，请将其视为单独注册。

期望的结果

ID  Start_dt    End_dt
A   1/1/2010    12/31/2012
A   1/1/2014    12/31/2014
A   1/1/2016    10/31/2016
A   1/1/2018    12/31/2018
B   1/1/2016    7/31/2017
B   1/1/2019    12/31/2019
C   1/1/2017    12/31/9999

这是一个Create Table查询：

if OBJECT_ID ('tempdb..#test1') is not null
drop table #test1
CREATE TABLE #test1 (
    ID varchar(10),
    Start_dt datetime,
    End_dt datetime
);

INSERT INTO #test1 VALUES ('A', '1/1/2010', '12/31/2010')
,('A', '1/1/2011', '12/31/2011')
,('A', '6/1/2012', '12/31/2012')
,('A', '1/1/2014', '12/31/2014')
,('A', '1/1/2016', '10/31/2016')
,('A', '1/1/2018', '12/31/2018')

,('B', '1/1/2016', '2/29/2016')
,('B', '3/1/2016', '10/31/2016')
,('B', '1/1/2017', '7/31/2017')
,('B', '1/1/2019', '12/31/9999')

,('C', '1/1/2017', '12/31/2017')
,('C', '1/1/2017', '12/31/2018')
,('C', '1/1/2019', '12/31/2999')

我一直试图解决这个问题好几天，但尝试过自联接，循环但没有找到一个好的解决方案。有人可以帮忙吗？

谢谢！

Answer 1

您可以使用lag()或累积的max()来获取上一个结束日期。然后将其与当前开始日期进行比较。

当差异超过一年时，则开始新组。这些新组的累积总和是否开始获得分组ID。

剩下的就是聚合：

select id, min(start_dt), max(end_dt)
from (select t1.*,
             sum(case when prev_end_dt > dateadd(year, -1, start_dt) then 0 else 1 end) over
                 (partition by id order by start_dt) as grp
      from (select t1.*,
                   max(end_dt) over (partition by id
                                      order by start_dt
                                      rows between unbounded preceding and 1 preceding
                                     ) as prev_end_dt
            from test1 t1
           ) t1
     ) t1
group by id, grp
order by id, min(start_dt);

Answer 2

你可以尝试这个查询

SELECT ID, StartDate, End_dt AS EndDate
FROM (
    SELECT * 
        , LAG(End_dt) OVER(PARTITION BY ID ORDER BY ID, Start_dt, End_dt) AS PrevEnd
        , DATEDIFF(DAY, LAG(End_dt) OVER(PARTITION BY ID ORDER BY ID, Start_dt, End_dt), Start_dt) AS DaysBreak
        , (
            CASE
                WHEN DATEDIFF(DAY, LAG(End_dt) OVER(PARTITION BY ID ORDER BY ID, Start_dt, End_dt), Start_dt) > 365 THEN Start_dt
                WHEN LAG(End_dt) OVER(PARTITION BY ID ORDER BY ID, Start_dt, End_dt) IS NULL THEN Start_dt
                ELSE NULL
            END
        ) AS StartDate
    FROM #test1
) a
WHERE StartDate IS NOT NULL