返回日期范围内的非重叠记录

Question

我有以下数据。我查看了很多关于重叠和非重叠日期的主题，但 none 似乎对我有所帮助。

===============================
PK  | StartDate  |  EndDate
===============================
1   | 2016-05-01 |  2016-05-02
2   | 2016-05-02 |  2016-05-03
3   | 2016-05-03 |  2016-05-04
4   | 2016-05-04 |  2016-05-05
5   | 2016-05-07 |  2016-06-08
===============================

从这个 table 使用 SQL 查询我想 return 重叠日期中的第一条记录或者基本上

===============================
PK  | StartDate  |  EndDate
===============================
1   | 2016-05-01 |  2016-05-02
3   | 2016-05-03 |  2016-05-04
5   | 2016-05-07 |  2016-06-08
===============================

我一直在为这个查询苦苦挣扎，想知道这是否真的可行而不会对性能造成太大影响，如果在后端完成或使用 SQL 查询是否更好，因为我相信我在后端做会更容易。

Answer 1

需要加入以首先找到所有重叠的列中的日期，然后只找到 MIN(dates)。

重叠日期范围 Start/End 的最小值

DROP TABLE IF EXISTS #Dates
CREATE TABLE #Dates (PK INT IDENTITY(1,1),StartDate DATE,EndDate DATE)
INSERT INTO #Dates VALUES
('2016-05-01','2016-05-02')
,('2016-05-02','2016-05-03')
,('2016-05-03','2016-05-04')
,('2016-05-04','2016-05-05')
,('2016-05-07','2016-06-08')

SELECT A.PK
    ,StartDate = MIN(C.StartDate)
        ,EndDate = MIN(C.EndDate)
FROM #Dates AS A
INNER JOIN #Dates AS B
    ON A.PK < B.PK /*Only join 1 way and don't join to itself*/
    /*Find any overlap*/
    AND A.StartDate <= B.EndDate
    AND A.EndDate >= B.StartDate
CROSS APPLY (VALUES /*Puts in unpivoted(vertical) format so can run MIN() function*/
                (A.StartDate,A.EndDate)
                ,(B.StartDate,B.EndDate)
) AS C(StartDate,EndDate)           
GROUP BY A.PK

Answer 2

这可以通过创建一个新列并将其分区以仅获取第一行来实现。

declare @tbl table
(pk int identity,StartDate date,EndDate date)

insert into @tbl
values('2016-05-01','2016-05-02')
,('2016-05-02','2016-05-03')
,('2016-05-03','2016-05-04')
,('2016-05-04','2016-05-05')
,('2016-05-07','2016-06-08')

select pk,startdate,enddate  from(select pk,startdate,enddate 
,ROW_NUMBER()over(partition by [overlappingdates] order by startdate)rn
from(
select *,case when ROW_NUMBER()over(order by startdate) % 2 = 0 
then StartDate else EndDate end as [overlappingdates]
from
@tbl
)t
)t
where t.rn = 1

返回日期范围内的非重叠记录

Returning non-overlapping records within a date range

sql

tsql

sql-server

重叠日期范围 Start/End 的最小值