Related
I have a sqlite dataset like this
Startdate | Enddate | ID
2019-04-29 | 2019-05-04 | 12
2019-04-23 | 2019-04-25 | 533
2019-04-23 | 2019-04-24 | 44
2019-04-24 | 2019-04-25 | 79
I'm trying to get an output that is sorted in range from startdate to startdate plus day in a loop until last Endate.
The plan is to get all observation from min(Startdate) to min(Startdate) +1 and min(Startdate) plus +2 and so one
Range | ID
2019-04-23 2019-04-24 | 44
2019-04-23 2019-04-25 | 44
2019-04-23 2019-04-25 | 533
2019-04-23 2019-04-25 | 79
2019-04-23 2019-05-04 | 44
2019-04-23 2019-05-04 | 533
2019-04-23 2019-05-04 | 79
2019-04-23 2019-05-04 | 12
I'm not sure have to achieve this
I believe that the following will provide the results that you want :-
WITH cte(sdate,edate) AS
(
SELECT (SELECT min(startdate) FROM mytable),(SELECT min(startdate) FROM mytable)
UNION ALL
SELECT sdate,date(edate,'+1 days')
FROM cte
WHERE edate <= (
SELECT max(enddate) FROM mytable
)
LIMIT 1000 /* just in case limit to 1000 rows */
)
SELECT sdate||' '||edate AS Range, id
FROM cte
JOIN mytable ON startdate >= sdate
AND enddate <= edate
AND edate IN (SELECT enddate FROM mytable)
Example/Test/Demo
DROP TABLE IF EXISTS mytable;
CREATE TABLE IF NOT EXISTS mytable (startdate TEXT, enddate TEXT, id INTEGER PRIMARY KEY);
INSERT INTO mytable VALUES
('2019-04-29','2019-05-04',12),
('2019-04-23','2019-04-25',533),
('2019-04-23','2019-04-24',44),
('2019-04-24','2019-04-25',79)
;
WITH cte(sdate,edate) AS
(
SELECT (SELECT min(startdate) FROM mytable),(SELECT min(startdate) FROM mytable)
UNION ALL
SELECT sdate,date(edate,'+1 days')
FROM cte
WHERE edate <= (
SELECT max(enddate) FROM mytable
)
LIMIT 1000 /* just in case limit to 1000 rows */
)
SELECT sdate||' '||edate AS Range, id
FROM cte
JOIN mytable ON startdate >= sdate
AND enddate <= edate
AND edate IN (SELECT enddate FROM mytable)
;
DROP TABLE IF EXISTS mytable;
The result is :-
The only difference being the order of the ID column (I can't see any order from your expected result)
As per the comment LIMIT 1000 is not required
My knowledge is pretty basic so your help would be highly appreciated.
I'm trying to return the same row multiple times when it meets the condition (I only have access to select query).
I have a table of more than 500000 records with Customer ID, Start Date and End Date, where end date could be null.
I am trying to add a new column called Week_No and list all rows accordingly. For example if the date range is more than one week, then the row must be returned multiple times with corresponding week number. Also I would like to count overlapping days, which will never be more than 7 (week) per row and then count unavailable days using second table.
Sample data below
t1
ID | Start_Date | End_Date
000001 | 12/12/2017 | 03/01/2018
000002 | 13/01/2018 |
000003 | 02/01/2018 | 11/01/2018
...
t2
ID | Unavailable
000002 | 14/01/2018
000003 | 03/01/2018
000003 | 04/01/2018
000003 | 08/01/2018
...
I cannot pass the stage of adding week no. I have tried using CASE and UNION ALL but keep getting errors.
declare #week01start datetime = '2018-01-01 00:00:00'
declare #week01end datetime = '2018-01-07 00:00:00'
declare #week02start datetime = '2018-01-08 00:00:00'
declare #week02end datetime = '2018-01-14 00:00:00'
...
SELECT
ID,
'01' as Week_No,
'2018' as YEAR,
Start_Date,
End_Date
FROM t1
WHERE (Start_Date <= #week01end and End_Date >= #week01start)
or (Start_Date <= #week01end and End_Date is null)
UNION ALL
SELECT
ID,
'02' as Week_No,
'2018' as YEAR,
Start_Date,
End_Date
FROM t1
WHERE (Start_Date <= #week02end and End_Date >= #week02start)
or (Start_Date <= #week02end and End_Date is null)
...
The new table should look like this
ID | Week_No | Year | Start_Date | End_Date | Overlap | Unavail_Days
000001 | 01 | 2018 | 12/12/2017 | 03/01/2018 | 3 |
000002 | 02 | 2018 | 13/01/2018 | | 2 | 1
000003 | 01 | 2018 | 02/01/2018 | 11/01/2018 | 6 | 2
000003 | 02 | 2018 | 02/01/2018 | 11/01/2018 | 4 | 1
...
business wise i cannot understand what you are trying to achieve. You can use the following code though to calculate your overlapping days etc. I did it the way you asked, but i would recommend a separate table, like a Time dimension to produce a "cleaner" solution
/*sample data set in temp table*/
select '000001' as id, '2017-12-12'as start_dt, ' 2018-01-03' as end_dt into #tmp union
select '000002' as id, '2018-01-13 'as start_dt, null as end_dt union
select '000003' as id, '2018-01-02' as start_dt, '2018-01-11' as end_dt
/*calculate week numbers and week diff according to dates*/
select *,
DATEPART(WK,start_dt) as start_weekNumber,
DATEPART(WK,end_dt) as end_weekNumber,
case
when DATEPART(WK,end_dt) - DATEPART(WK,start_dt) > 0 then (DATEPART(WK,end_dt) - DATEPART(WK,start_dt)) +1
else (52 - DATEPART(WK,start_dt)) + DATEPART(WK,end_dt)
end as WeekDiff
into #tmp1
from
(
SELECT *,DATEADD(DAY, 2 - DATEPART(WEEKDAY, start_dt), CAST(start_dt AS DATE)) [start_dt_Week_Start_Date],
DATEADD(DAY, 8 - DATEPART(WEEKDAY, start_dt), CAST(start_dt AS DATE)) [startdt_Week_End_Date],
DATEADD(DAY, 2 - DATEPART(WEEKDAY, end_dt), CAST(end_dt AS DATE)) [end_dt_Week_Start_Date],
DATEADD(DAY, 8 - DATEPART(WEEKDAY, end_dt), CAST(end_dt AS DATE)) [end_dt_Week_End_Date]
from #tmp
) s
/*cte used to create duplicates when week diff is over 1*/
;with x as
(
SELECT TOP (10) rn = ROW_NUMBER() --modify the max you want
OVER (ORDER BY [object_id])
FROM sys.all_columns
ORDER BY [object_id]
)
/*final query*/
select --*
ID,
start_weekNumber+ (r-1) as Week,
DATEPART(YY,start_dt) as [YEAR],
start_dt,
end_dt,
null as Overlap,
null as unavailable_days
from
(
select *,
ROW_NUMBER() over (partition by id order by id) r
from
(
select d.* from x
CROSS JOIN #tmp1 AS d
WHERE x.rn <= d.WeekDiff
union all
select * from #tmp1
where WeekDiff is null
) a
)a_ext
order by id,start_weekNumber
--drop table #tmp1,#tmp
The above will produce the results you want except the overlap and unavailable columns. Instead of just counting weeks, i added the number of week in the year using start_dt, but you can change that if you don't like it:
ID Week YEAR start_dt end_dt Overlap unavailable_days
000001 50 2017 2017-12-12 2018-01-03 NULL NULL
000001 51 2017 2017-12-12 2018-01-03 NULL NULL
000001 52 2017 2017-12-12 2018-01-03 NULL NULL
000002 2 2018 2018-01-13 NULL NULL NULL
000003 1 2018 2018-01-02 2018-01-11 NULL NULL
000003 2 2018 2018-01-02 2018-01-11 NULL NULL
I have a table which describes a value which is valid for a certain period of days / months.
The table looks like this:
+----+------------+------------+-------+
| Id | From | To | Value |
+----+------------+------------+-------+
| 1 | 2018-01-01 | 2018-03-31 | ValA |
| 2 | 2018-01-16 | NULL | ValB |
| 3 | 2018-04-01 | 2018-05-12 | ValC |
+----+------------+------------+-------+
As you can see, the only value still valid on this day is ValB (To is nullable, From isn't).
I am trying to achieve a view on this table like this (assuming I render this view someday in july 2018):
+----------+------------+------------+-------+
| RecordId | From | To | Value |
+----------+------------+------------+-------+
| 1 | 2018-01-01 | 2018-01-31 | ValA |
| 1 | 2018-02-01 | 2018-02-28 | ValA |
| 1 | 2018-03-01 | 2018-03-31 | ValA |
| 2 | 2018-01-16 | 2018-01-31 | ValB |
| 2 | 2018-02-01 | 2018-02-28 | ValB |
| 2 | 2018-03-01 | 2018-03-31 | ValB |
| 2 | 2018-04-01 | 2018-04-30 | ValB |
| 2 | 2018-05-01 | 2018-05-31 | ValB |
| 2 | 2018-06-01 | 2018-06-30 | ValB |
| 3 | 2018-04-01 | 2018-04-30 | ValC |
| 3 | 2018-05-01 | 2018-05-12 | ValC |
+----------+------------+------------+-------+
This view basically creates a record for each record in the table, but splitted by month, using the correct dates (especially minding the start and end dates that are not on the first or the last day of the month).
The one record without a To date (so it's still valid to this day), is rendered until the last day of the month in which I render the view, so at the time of writing, this is july 2018.
This is a simple example, but a solution will seriously help me along. I'll need this for multiple calculations, including proration of amounts.
Here's a table script and some insert statements that you can use:
CREATE TABLE [dbo].[Test]
(
[Id] INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
[From] SMALLDATETIME NOT NULL,
[To] SMALLDATETIME NULL,
[Value] NVARCHAR(100) NOT NULL
)
INSERT INTO dbo.Test ([From],[To],[Value])
VALUES
('2018-01-01','2018-03-31','ValA'),
('2018-01-16',null,'ValB'),
('2018-04-01','2018-05-12','ValC');
Thanks in advance!
Generate all months that might appear on your values (with start and end), then join where each month overlaps the period of your values. Change the result so if a month doesn't overlap fully, you just display the limits of your period.
DECLARE #StartDate DATE = '2018-01-01'
DECLARE #EndDate DATE = '2020-01-01'
;WITH GeneratedMonths AS
(
SELECT
StartDate = #StartDate,
EndDate = EOMONTH(#StartDate)
UNION ALL
SELECT
StartDate = DATEADD(MONTH, 1, G.StartDate),
EndDate = EOMONTH(DATEADD(MONTH, 1, G.StartDate))
FROM
GeneratedMonths AS G
WHERE
DATEADD(MONTH, 1, G.StartDate) < #EndDate
)
SELECT
T.Id,
[From] = CASE WHEN T.[From] >= G.StartDate THEN T.[From] ELSE G.StartDate END,
[To] = CASE WHEN G.EndDate >= T.[To] THEN T.[To] ELSE G.EndDate END,
T.Value
FROM
dbo.Test AS T
INNER JOIN GeneratedMonths AS G ON
G.EndDate >= T.[From] AND
G.StartDate <= ISNULL(T.[To], GETDATE())
ORDER BY
T.Id,
G.StartDate
OPTION
(MAXRECURSION 3000)
Recursive cte is very simple way if you don't have a large dataset :
with t as (
select id, [from], [to], Value
from Test
union all
select id, dateadd(mm, 1, [from]), [to], value
from t
where dateadd(mm, 1, [from]) < coalesce([to], getdate())
)
select id, [from], (case when eomonth([from]) <= coalesce([to], cast(getdate() as date))
then eomonth([from]) else coalesce([to], eomonth([from]))
end) as [To],
Value
from t
order by id;
By using date functions and recursive CTE.
with cte as
(
Select Id, Cast([From] as date) as [From], EOMONTH([from]) as [To1],
COALESCE([To],EOMONTH(GETDATE())) AS [TO],Value from test
UNION ALL
Select Id, DATEADD(DAY,1,[To1]),
CASE when EOMONTH(DATEADD(DAY,1,[To1])) > [To] THEN CAST([To] AS DATE)
ELSE EOMONTH(DATEADD(DAY,1,[To1])) END as [To1],
[To],Value from cte where TO1 <> [To]
)
Select Id, [From],[To1] as [To], Value from cte order by Id
#EzLo your solution is good but require setting 2 variables with fixed values.
To avoid this you can do recursive CTE on real data
WITH A AS(
SELECT
T.Id, CAST(T.[From] AS DATE) AS [From], CASE WHEN T.[To]<EOMONTH(T.[From], 0) THEN T.[To] ELSE EOMONTH(T.[From], 0) END AS [To], T.Value, CAST(0 AS INTEGER) AS ADD_M
FROM
TEST T
UNION ALL
SELECT
T.Id, DATEADD(DAY, 1, EOMONTH(T.[From], -1+(A.ADD_M+1))), CASE WHEN T.[To]<EOMONTH(T.[From], A.ADD_M+1) THEN T.[To] ELSE EOMONTH(T.[From], A.ADD_M+1) END AS [To], T.Value, A.ADD_M+1
FROM
TEST T
INNER JOIN A ON T.Id=A.Id AND DATEADD(MONTH, A.ADD_M+1, T.[From]) < CASE WHEN T.[To] IS NULL THEN CAST(GETDATE() AS DATE) ELSE T.[To] END
)
SELECT
A.[Id], A.[From], A.[To], A.[Value]
FROM
A
ORDER BY A.[Id], A.[From]
I am trying to take given date ranges found in a data set and divide them into unique rows for each day in the range (example below). Doing the opposite in SQL is pretty straight forward, but I am struggling to achieve the desired query output.
Beginning data:
ITEM START_DATE END_DATE
A 1/1/2015 1/5/2015
B 2/5/2015 2/7/2015
Desired query output:
ITEM DATE_COVERED
A 1/1/2015
A 1/2/2015
A 1/3/2015
A 1/4/2015
A 1/5/2015
B 2/5/2015
B 2/6/2015
B 2/7/2015
The fastest way will be some tally table:
DECLARE #t TABLE
(
ITEM CHAR(1) ,
START_DATE DATE ,
END_DATE DATE
)
INSERT INTO #t
VALUES ( 'A', '1/1/2015', '1/5/2015' ),
( 'B', '2/5/2015', '2/7/2015' )
;WITH cte AS(SELECT -1 + ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) d FROM
(VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) t1(n) CROSS JOIN
(VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) t2(n) CROSS JOIN
(VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) t3(n) CROSS JOIN
(VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) t4(n))
SELECT t.ITEM, ca.DATE_COVERED FROM #t t
CROSS APPLY(SELECT DATEADD(dd, d, t.START_DATE) AS DATE_COVERED
FROM cte
WHERE DATEADD(dd, d, t.START_DATE) BETWEEN t.START_DATE AND t.END_DATE) ca
ORDER BY t.ITEM, ca.DATE_COVERED
Query:
SQLFiddleExample
SELECT t.ITEM,
DATEADD(day,n.number, t.START_DATE) AS DATE_COVERED
FROM Table1 t,
(SELECT number
FROM master..spt_values
WHERE [type] = 'P') n
WHERE START_DATE <= DATEADD(day,n.number, t.START_DATE)
AND END_DATE >= DATEADD(day,n.number, t.START_DATE)
Result:
| ITEM | DATE_COVERED |
|------|--------------|
| A | 2015-01-01 |
| A | 2015-01-02 |
| A | 2015-01-03 |
| A | 2015-01-04 |
| A | 2015-01-05 |
| B | 2015-02-05 |
| B | 2015-02-06 |
| B | 2015-02-07 |
NOTE: this only works if the difference between your startdate and enddate is a maximum of 2047 days (master..spt_values only allows 0..2047 range of values)
select item, dateadd(d,v.number,d.start_date) adate
from begindata d
join master..spt_values v on v.type='P'
and v.number between 0 and datediff(d, start_date, end_date)
order by adate;
I'd like to say I did this myself but I got the code from this
Here is a fiddle with your expected result
TRY THIS...
CREATE TABLE Table1
([ITEM] varchar(1), [START_DATE] date, [END_DATE] date)
;
INSERT INTO Table1
([ITEM], [START_DATE], [END_DATE])
VALUES ('A', '2015-01-01', '2015-01-05'), ('B', '2015-02-05', 2015-02-07');
WITH Days
AS ( SELECT ITEM, START_DATE AS [Date], 1 AS [level] from Table1
UNION ALL
SELECT TABLE1.ITEM, DATEADD(DAY, 1, [Date]), [level] + 1
FROM Days,Table1
WHERE DAYS.ITEM=TABLE1.ITEM AND [Date] < END_DATE )
SELECT distinct [Date]
FROM Days
DEMO
Using SQL Server 2008 R2,
I'm trying to combine date ranges into the maximum date range given that one end date is next to the following start date.
The data is about different employments. Some employees may have ended their employment and have rejoined at a later time. Those should count as two different employments (example ID 5). Some people have different types of employment, running after each other (enddate and startdate neck-to-neck), in this case it should be considered as one employment in total (example ID 30).
An employment period that has not ended has an enddate that is null.
Some examples is probably enlightening:
declare #t as table (employmentid int, startdate datetime, enddate datetime)
insert into #t values
(5, '2007-12-03', '2011-08-26'),
(5, '2013-05-02', null),
(30, '2006-10-02', '2011-01-16'),
(30, '2011-01-17', '2012-08-12'),
(30, '2012-08-13', null),
(66, '2007-09-24', null)
-- expected outcome
EmploymentId StartDate EndDate
5 2007-12-03 2011-08-26
5 2013-05-02 NULL
30 2006-10-02 NULL
66 2007-09-24 NULL
I've been trying different "islands-and-gaps" techniques but haven't been able to crack this one.
The strange bit you see with my use of the date '31211231' is just a very large date to handle your "no-end-date" scenario. I have assumed you won't really have many date ranges per employee, so I've used a simple Recursive Common Table Expression to combine the ranges.
To make it run faster, the starting anchor query keeps only those dates that will not link up to a prior range (per employee). The rest is just tree-walking the date ranges and growing the range. The final GROUP BY keeps only the largest date range built up per starting ANCHOR (employmentid, startdate) combination.
SQL Fiddle
MS SQL Server 2008 Schema Setup:
create table Tbl (
employmentid int,
startdate datetime,
enddate datetime);
insert Tbl values
(5, '2007-12-03', '2011-08-26'),
(5, '2013-05-02', null),
(30, '2006-10-02', '2011-01-16'),
(30, '2011-01-17', '2012-08-12'),
(30, '2012-08-13', null),
(66, '2007-09-24', null);
/*
-- expected outcome
EmploymentId StartDate EndDate
5 2007-12-03 2011-08-26
5 2013-05-02 NULL
30 2006-10-02 NULL
66 2007-09-24 NULL
*/
Query 1:
;with cte as (
select a.employmentid, a.startdate, a.enddate
from Tbl a
left join Tbl b on a.employmentid=b.employmentid and a.startdate-1=b.enddate
where b.employmentid is null
union all
select a.employmentid, a.startdate, b.enddate
from cte a
join Tbl b on a.employmentid=b.employmentid and b.startdate-1=a.enddate
)
select employmentid,
startdate,
nullif(max(isnull(enddate,'32121231')),'32121231') enddate
from cte
group by employmentid, startdate
order by employmentid
Results:
| EMPLOYMENTID | STARTDATE | ENDDATE |
-----------------------------------------------------------------------------------
| 5 | December, 03 2007 00:00:00+0000 | August, 26 2011 00:00:00+0000 |
| 5 | May, 02 2013 00:00:00+0000 | (null) |
| 30 | October, 02 2006 00:00:00+0000 | (null) |
| 66 | September, 24 2007 00:00:00+0000 | (null) |
SET NOCOUNT ON
DECLARE #T TABLE(ID INT,FromDate DATETIME, ToDate DATETIME)
INSERT INTO #T(ID,FromDate,ToDate)
SELECT 1,'20090801','20090803' UNION ALL
SELECT 2,'20090802','20090809' UNION ALL
SELECT 3,'20090805','20090806' UNION ALL
SELECT 4,'20090812','20090813' UNION ALL
SELECT 5,'20090811','20090812' UNION ALL
SELECT 6,'20090802','20090802'
SELECT ROW_NUMBER() OVER(ORDER BY s1.FromDate) AS ID,
s1.FromDate,
MIN(t1.ToDate) AS ToDate
FROM #T s1
INNER JOIN #T t1 ON s1.FromDate <= t1.ToDate
AND NOT EXISTS(SELECT * FROM #T t2
WHERE t1.ToDate >= t2.FromDate
AND t1.ToDate < t2.ToDate)
WHERE NOT EXISTS(SELECT * FROM #T s2
WHERE s1.FromDate > s2.FromDate
AND s1.FromDate <= s2.ToDate)
GROUP BY s1.FromDate
ORDER BY s1.FromDate
An alternative solution that uses window functions rather than recursive CTEs
SELECT
employmentid,
MIN(startdate) as startdate,
NULLIF(MAX(COALESCE(enddate,'9999-01-01')), '9999-01-01') as enddate
FROM (
SELECT
employmentid,
startdate,
enddate,
DATEADD(
DAY,
-COALESCE(
SUM(DATEDIFF(DAY, startdate, enddate)+1) OVER (PARTITION BY employmentid ORDER BY startdate ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING),
0
),
startdate
) as grp
FROM #t
) withGroup
GROUP BY employmentid, grp
ORDER BY employmentid, startdate
This works by calculating a grp value that will be the same for all consecutive rows. This is achieved by:
Determine totals days the span occupies (+1 as the dates are inclusive)
SELECT *, DATEDIFF(DAY, startdate, enddate)+1 as daysSpanned FROM #t
Cumulative sum the days spanned for each employment, ordered by startdate. This gives us the total days spanned by all the previous employment spans
We coalesce with 0 to ensure we dont have NULLs in our cumulative sum of days spanned
We do not include current row in our cumulative sum, this is because we will use the value against startdate rather than enddate (we cant use it against enddate because of the NULLs)
SELECT *, COALESCE(
SUM(daysSpanned) OVER (
PARTITION BY employmentid
ORDER BY startdate
ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
)
,0
) as cumulativeDaysSpanned
FROM (
SELECT *, DATEDIFF(DAY, startdate, enddate)+1 as daysSpanned FROM #t
) inner1
Subtract the cumulative days from the startdate to get our grp. This is the crux of the solution.
If the start date increases at the same rate as the days spanned then the days are consecutive, and subtracting the two will give us the same value.
If the startdate increases faster than the days spanned then there is a gap and we will get a new grp value greater than the previous one.
Although grp is a date, the date itself is meaningless we are using just as a grouping value
SELECT *, DATEADD(DAY, -cumulativeDaysSpanned, startdate) as grp
FROM (
SELECT *, COALESCE(
SUM(daysSpanned) OVER (
PARTITION BY employmentid
ORDER BY startdate
ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
)
,0
) as cumulativeDaysSpanned
FROM (
SELECT *, DATEDIFF(DAY, startdate, enddate)+1 as daysSpanned FROM #t
) inner1
) inner2
With the results
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| employmentid | startdate | enddate | daysSpanned | cumulativeDaysSpanned | grp |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 5 | 2007-12-03 00:00:00.000 | 2011-08-26 00:00:00.000 | 1363 | 0 | 2007-12-03 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 5 | 2013-05-02 00:00:00.000 | NULL | NULL | 1363 | 2009-08-08 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 30 | 2006-10-02 00:00:00.000 | 2011-01-16 00:00:00.000 | 1568 | 0 | 2006-10-02 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 30 | 2011-01-17 00:00:00.000 | 2012-08-12 00:00:00.000 | 574 | 1568 | 2006-10-02 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 30 | 2012-08-13 00:00:00.000 | NULL | NULL | 2142 | 2006-10-02 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
| 66 | 2007-09-24 00:00:00.000 | NULL | NULL | 0 | 2007-09-24 00:00:00.000 |
+--------------+-------------------------+-------------------------+-------------+-----------------------+-------------------------+
Finally we can GROUP BY grp to get the get rid of the consecutive days.
Use MIN and MAX to get the new startdate and endate
To handle the NULL enddate we give them a large value to get picked up by MAX then convert them back to NULL again
SELECT
employmentid,
MIN(startdate) as startdate,
NULLIF(MAX(COALESCE(enddate,'9999-01-01')), '9999-01-01') as enddate
FROM (
SELECT *, DATEADD(DAY, -cumulativeDaysSpanned, startdate) as grp
FROM (
SELECT *, COALESCE(
SUM(daysSpanned) OVER (
PARTITION BY employmentid
ORDER BY startdate
ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
)
,0
) as cumulativeDaysSpanned
FROM (
SELECT *, DATEDIFF(DAY, startdate, enddate)+1 as daysSpanned FROM #t
) inner1
) inner2
) inner3
GROUP BY employmentid, grp
ORDER BY employmentid, startdate
To get the desired result
+--------------+-------------------------+-------------------------+
| employmentid | startdate | enddate |
+--------------+-------------------------+-------------------------+
| 5 | 2007-12-03 00:00:00.000 | 2011-08-26 00:00:00.000 |
+--------------+-------------------------+-------------------------+
| 5 | 2013-05-02 00:00:00.000 | NULL |
+--------------+-------------------------+-------------------------+
| 30 | 2006-10-02 00:00:00.000 | NULL |
+--------------+-------------------------+-------------------------+
| 66 | 2007-09-24 00:00:00.000 | NULL |
+--------------+-------------------------+-------------------------+
We can combine the inner queries to get the query at the start of this answer. Which is shorter, but less explainable
Limitations of all this required that
there are no overlaps of startdate and enddate for an employment. This could produce collisions in our grp.
startdate is not NULL. However this could be overcome by replacing NULL start dates with small date values
Future developers can decipher the window black magic you performed
A modified script for combining all overlapping periods. For example
01.01.2001-01.01.2010
05.05.2005-05.05.2015
will give one period:
01.01.2001-05.05.2015
tbl.enddate must be completed
;WITH cte
AS(
SELECT
a.employmentid
,a.startdate
,a.enddate
from tbl a
left join tbl c on a.employmentid=c.employmentid
and a.startdate > c.startdate
and a.startdate <= dateadd(day, 1, c.enddate)
WHERE c.employmentid IS NULL
UNION all
SELECT
a.employmentid
,a.startdate
,a.enddate
from cte a
inner join tbl c on a.startdate=c.startdate
and (c.startdate = dateadd(day, 1, a.enddate) or (c.enddate > a.enddate and c.startdate <= a.enddate))
)
select distinct employmentid,
startdate,
nullif(max(enddate),'31.12.2099') enddate
from cte
group by employmentid, startdate