I was hoping someone might help me on this one. I have two tables that need to be joined on the nearest date (nearest before date). I have found with some searching a way to do this using the DATEDIFF and Row_Number functions, but the output is not quite what I want. Here is what i am trying to do:
CREATE TABLE #OPS ([Date] Date, [Runtime] FLOAT, [INTERVAL] INT)
INSERT INTO #OPS Values
( '2015-02-09',29540.3,12),
('2015-02-16',29661.7, 10),
('2015-03-02',29993.7,10),
('2015-03-09',30161.7,12),
('2015-03-16',30333.4,12),
('2015-03-23',30337.9,5),
('2015-03-30',30506.9,12),
('2015-04-06',30628.1,6),
('2015-04-13',30795,4),
('2015-04-20',30961.2,6)
SELECT * FROM #OPS
CREATE TABLE #APPS ([Date] DATE, [Value] INT)
INSERT INTO #APPS Values
('2015-03-05', 1000),('2015-03-27', 1040), ('2015-04-17', 1070)
;WITH Nearest_date AS
(
SELECT
t1.*, t2.Date as date2, t2.Value,
ROW_NUMBER() OVER
(
PARTITION BY t1.[Date]
ORDER BY t2.[Date] DESC
) AS RowNum
FROM #OPS t1
LEFT JOIN #APPS t2
ON t2.[Date] <= t1.[Date]
)
SELECT *
FROM Nearest_date
WHERE RowNum = 1
ORDER BY Date ASC
--This is what I get
Date Runtime INTERVAL date2 Value
2/9/2015 29540.3 12 NULL NULL
2/16/2015 29661.7 10 NULL NULL
3/2/2015 29993.7 10 NULL NULL
3/9/2015 30161.7 12 3/5/2015 1000
3/16/2015 30333.4 12 3/5/2015 1000
3/23/2015 30337.9 5 3/5/2015 1000
3/30/2015 30506.9 12 3/27/2015 1040
4/6/2015 30628.1 6 3/27/2015 1040
4/13/2015 30795 4 3/27/2015 1040
4/20/2015 30961.2 6 4/17/2015 1070
-- This is what I want
Date Runtime INTERVAL date2 Value
2/9/2015 29540.3 12 NULL NULL
2/16/2015 29661.7 10 NULL NULL
3/2/2015 29993.7 10 NULL NULL
3/9/2015 30161.7 12 3/5/2015 1000
3/16/2015 30333.4 12 NULL NULL
3/23/2015 30337.9 5 NULL NULL
3/30/2015 30506.9 12 3/27/2015 1040
4/6/2015 30628.1 6 NULL NULL
4/13/2015 30795 4 NULL NULL
4/20/2015 30961.2 6 4/17/2015 1070
You can see that I want to select the nearest date that date compared against all dates in the second table. The query I created shows the same date for multiple values - when only one of those dates is truly the closest. Any help would be, as always, massively appreciated. -- running MSSQL 2014
Using OUTER APPLY and LEFT JOIN:
SQL Fiddle
SELECT
o.*,
Date2 = t.Date,
t.Value
FROM #OPS o
LEFT JOIN(
SELECT
a.*, Date2 = x.Date
FROM #APPS a
OUTER APPLY(
SELECT TOP 1 *
FROM #OPS
WHERE
[Date] <= a.Date
ORDER BY [Date] DESC
)x
)t
ON t.Date2 = o.Date
Related
I have table of products and their sales quantity in months.
Product Month Qty
A 2018-01-01 5
A 2018-02-01 3
A 2018-05-01 5
B 2018-08-01 10
B 2018-10-01 12
...
I'd like to first fill in the data gap between each product's min and max dates like below:
Product Month Qty
A 2018-01-01 5
A 2018-02-01 3
A 2018-03-01 0
A 2018-04-01 0
A 2018-05-01 5
B 2018-08-01 10
B 2018-09-01 0
B 2018-10-01 12
...
Then I would need to perform an accumulation of each product's sales quantity by month.
Product Month total_Qty
A 2018-01-01 5
A 2018-02-01 8
A 2018-03-01 8
A 2018-04-01 8
A 2018-05-01 13
B 2018-08-01 10
B 2018-09-01 10
B 2018-10-01 22
...
I fumbled over the "cross join" clause, however it seems to generate some unexpected results for me. Could someone help to give a hint how I can achieve this in SQL?
Thanks a lot in advance.
I think a recursive CTE is a simple way to do this. The code is just:
with cte as (
select product, min(mon) as mon, max(mon) as end_mon
from t
group by product
union all
select product, dateadd(month, 1, mon), end_mon
from cte
where mon < end_mon
)
select cte.product, cte.mon, coalesce(qty, 0) as qty
from cte left join
t
on t.product = cte.product and t.mon = cte.mon;
Here is a db<>fiddle.
Hi i think this example can help you and perform what you excepted :
CREATE TABLE #MyTable
(Product varchar(10),
ProductMonth DATETIME,
Qty int
);
GO
CREATE TABLE #MyTableTempDate
(
FullMonth DATETIME
);
GO
INSERT INTO #MyTable
SELECT 'A', '2019-01-01', 214
UNION
SELECT 'A', '2019-02-01', 4
UNION
SELECT 'A', '2019-03-01', 50
UNION
SELECT 'B', '2019-01-01', 214
UNION
SELECT 'B', '2019-02-01', 10
UNION
SELECT 'C', '2019-04-01', 150
INSERT INTO #MyTableTempDate
SELECT '2019-01-01'
UNION
SELECT '2019-02-01'
UNION
SELECT '2019-03-01'
UNION
SELECT '2019-04-01'
UNION
SELECT '2019-05-01'
UNION
SELECT '2019-06-01'
UNION
SELECT '2019-07-01';
------------- FOR NEWER SQL SERVER VERSION > 2005
WITH MyCTE AS
(
SELECT T.Product, T.ProductMonth AS 'MMonth', T.Qty
FROM #MyTable T
UNION
SELECT T.Product, TD.FullMonth AS 'MMonth', 0 AS 'Qty'
FROM #MyTable T, #MyTableTempDate TD
WHERE NOT EXISTS (SELECT 1 FROM #MyTable TT WHERE TT.Product = T.Product AND TD.FullMonth = TT.ProductMonth)
)
-- SELECT * FROM MyCTE;
SELECT Product, MMonth, Qty, SUM( Qty) OVER(PARTITION BY Product ORDER BY Product
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as 'TotalQty'
FROM MyCTE
ORDER BY Product, MMonth ASC;
DROP TABLE #MyTable
DROP TABLE #MyTableTempDate
I have other way to perform this in lower SQL Server Version (like 2005 and lower)
It's a SELECT on SELECT if it's your case let me know and i provide some other example.
You can create the months with a recursive CTE
DECLARE #MyTable TABLE
(
ProductID CHAR(1),
Date DATE,
Amount INT
)
INSERT INTO #MyTable
VALUES
('A','2018-01-01', 5),
('A','2018-02-01', 3),
('A','2018-05-01', 5),
('B','2018-08-01', 10),
('B','2018-10-01', 12)
DECLARE #StartDate DATE
DECLARE #EndDate DATE
SELECT #StartDate = MIN(Date), #EndDate = MAX(Date) FROM #MyTable
;WITH dates AS (
SELECT #StartDate AS Date
UNION ALL
SELECT DATEADD(Month, 1, Date)
FROM dates
WHERE Date < #EndDate
)
SELECT A.ProductID, d.Date, COALESCE(Amount,0) AS Amount, COALESCE(SUM(Amount) OVER(PARTITION BY A.ProductID ORDER BY A.ProductID, d.Date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW),0) AS Total
FROM
(
SELECT ProductID, MIN(date) as DateStart, MAX(date) as DateEnd
FROM #MyTable
GROUP BY ProductID -- As I read in your comments that you need different min and max dates per product
) A
JOIN dates d ON d.Date >= A.DateStart AND d.Date <= A.DateEnd
LEFT JOIN #MyTable T ON A.ProductID = T.ProductID AND T.Date = d.Date
ORDER BY A.ProductID, d.Date
Try this below
IF OBJECT_ID('tempdb..#Temp') IS NOT NULL
DROP TABLE #Temp
;WITH CTE(Product,[Month],Qty)
AS
(
SELECT 'A','2018-01-01', 5 UNION ALL
SELECT 'A','2018-02-01', 3 UNION ALL
SELECT 'A','2018-05-01', 5 UNION ALL
SELECT 'B','2018-08-01', 10 UNION ALL
SELECT 'D','2018-10-01', 12
)
SELECT ct.Product,[MonthDays],ct.Qty
INTO #Temp
FROM
(
SELECT c.Product,[Month],
ISNULL(Qty,0) AS Qty
FROM CTE c
)ct
RIGHT JOIN
(
SELECT -- This code is to get month data
CONVERT(VARCHAR(10),'2018-'+ RIGHT('00'+CAST(MONTH(DATEADD(MM, s.number, CONVERT(DATETIME, 0)))AS VARCHAR),2) +'-01',120) AS [MonthDays]
FROM master.dbo.spt_values s
WHERE [type] = 'P' AND s.number BETWEEN 0 AND 11
)DT
ON dt.[MonthDays] = ct.[Month]
SELECT
MAX(Product)OVER(ORDER BY [MonthDays])AS Product,
[MonthDays],
ISNULL(Qty,0) Qty,
SUM(ISNULL(Qty,0))OVER(ORDER BY [MonthDays]) As SumQty
FROM #Temp
Result
Product MonthDays Qty SumQty
------------------------------
A 2018-01-01 5 5
A 2018-02-01 3 8
A 2018-03-01 0 8
A 2018-04-01 0 8
A 2018-05-01 5 13
A 2018-06-01 0 13
A 2018-07-01 0 13
B 2018-08-01 10 23
B 2018-09-01 0 23
D 2018-10-01 12 35
D 2018-11-01 0 35
D 2018-12-01 0 35
First of all, i would divide month and year to get easier with statistics.
I will give you an example query, not based on your table but still helpful.
--here i create the table that will be used as calendar
Create Table MA_MonthYears (
Month int not null ,
year int not null
PRIMARY KEY ( month, year) )
--/////////////////
-- here i'm creating a procedure to fill the ma_monthyears table
declare #month as int
declare #year as int
set #month = 1
set #year = 2015
while ( #year != 2099 )
begin
insert into MA_MonthYears(Month, year)
select #month, #year
if #month < 12
set #month=#month+1
else
set #month=1
if #month = 1
set #year = #year + 1
end
--/////////////////
--here you are the possible result you are looking for
select SUM(Ma_saledocdetail.taxableamount) as Sold, MA_MonthYears.month , MA_MonthYears.year , item
from MA_MonthYears left outer join MA_SaleDocDetail on year(MA_SaleDocDetail.DocumentDate) = MA_MonthYears.year
and Month(ma_saledocdetail.documentdate) = MA_MonthYears.Month
group by MA_SaleDocDetail.Item, MA_MonthYears.year , MA_MonthYears.month
order by MA_MonthYears.year , MA_MonthYears.month
currently I am trying to figure out a join between to historized tables, where I want to synchronize both timeline.
As an example, I have the following two tables:
A
ID Value FROM TO
1 5 01.01.2018 31.03.2018
1 6 31.03.2018 08.04.2018
B A_FK Value FROM TO
1 1 50 01.02.2018 01.04.2018
2 1 51 04.04.2018 10.04.2018
As a baseline, I want to take the timeline of table A and join table B, including NULL values so that I know, for which times there is no fitting value.
The desired result should look like this:
C
Value_A Value_B FROM TO
5 NULL 01.01.2018 01.02.2018
5 50 01.02.2018 31.03.2018
6 50 31.03.2018 01.04.2018
6 NULL 01.04.2018 04.04.2018
6 51 04.04.2018 08.04.2018
Can you help me with this? I started, but can fail to align the wrong history - here my try:
with a as (SELECT *
FROM (VALUES (1,5,'01.01.2018','31.03.2018')
, (1,6,'31.03.2018','08.04.2018')
) A (ID, VALUE, FROM, TO)),
b as (
SELECT *
FROM (VALUES (1,1,50,'01.02.2018','01.04.2018')
, (2,1,51,'04.04.2018','10.04.2018')
) A (ID,A_FK, VALUE, FROM, TO)
)
select
a.value as value_a,
b.value as value_b,
max(a.from,b.from) as from,
min(a.to,b.to) as to
from a
left outer join b on
a.id = b.a_fk and
a.from < b.to and
a.to > b.from;
As you can see, it aligns, but not the way I expected it to.
Thank you for your help.
So as I suggested in the comments with the technique in my own answer from another question you can solve your problem.
Here is one solution.
The test data:
create table a (
id integer,
value integer,
dtfrom date,
dtto date
);
create table b(
id integer,
a_fk integer,
value integer,
dtfrom date,
dtto date
);
insert into a values
(1, 5, '2018-01-01', '2018-03-31'),
(1, 6, '2018-03-31', '2018-04-08');
insert into b values
(1, 1, 50, '2018-02-01', '2018-04-01'),
(2, 1, 51, '2018-04-04', '2018-04-10');
The trick part of this solution is to generate the date intervals that isn't in any of your tables such as 01.01.2018-01.02.2018 and 01.02.2018-31.03.2018 so in order to do that you must have all available dates as one table so I created a VIEW called timmings to make it easier:
create or replace view timmings as
select a.dtfrom dt from a inner join b on a.id=b.a_fk
union
select a.dtto from a inner join b on a.id=b.a_fk
union
select b.dtfrom from a inner join b on a.id=b.a_fk
union
select b.dtto from a inner join b on a.id=b.a_fk;
After that you need a query to generate all available periods (starts and ends) so it will be:
select t1.dt as start,
(select min(t2.dt)
from timmings t2
where t2.dt>t1.dt) as dend
from timmings t1
order by start;
This will result in (with your sample data):
start dend
01/01/2018 01/02/2018
01/02/2018 31/03/2018
31/03/2018 01/04/2018
01/04/2018 04/04/2018
04/04/2018 08/04/2018
08/04/2018 10/04/2018
10/04/2018 null
With that you can use it to get all available values from table a that intersects with the periods:
select a.id, a.value, tm.start, tm.dend
from (select t1.dt as start,
(select min(t2.dt)
from timmings t2
where t2.dt>t1.dt) as dend
from timmings t1) tm
left join a on tm.start >= a.dtfrom and tm.dend <= a.dtto
where a.id is not null
order by tm.start;
That results in:
id value start end
1 5 01/01/2018 01/02/2018
1 5 01/02/2018 31/03/2018
1 6 31/03/2018 01/04/2018
1 6 01/04/2018 04/04/2018
1 6 04/04/2018 08/04/2018
And finally you LEFT JOIN it with b table:
select x.value as valueA,
b.value as valueB,
x.start as "from",
x.dend as "to"
from (select a.id, a.value, tm.start, tm.dend
from (select t1.dt as start,
(select min(t2.dt)
from timmings t2
where t2.dt>t1.dt) as dend
from timmings t1) tm
left join a on tm.start >= a.dtfrom and tm.dend <= a.dtto
where a.id is not null
) x
left join b on b.a_fk = x.id
and b.dtfrom <= x.start
and b.dtto >= x.dend
order by x.start;
Which will give you the result you want:
valueA valueB start end
5 null 01/01/2018 01/02/2018
5 50 01/02/2018 31/03/2018
6 50 31/03/2018 01/04/2018
6 null 01/04/2018 04/04/2018
6 51 04/04/2018 08/04/2018
See the final solution working here: http://sqlfiddle.com/#!9/36418e/1 It is MySQL but since it is all SQL ANSI it will work just fine in DB2
There is an excellent Blog article about that
"Fun with Date Ranges" by John Maenpaa
And secondly if you have a chance to influence the DDL I would recommend to have a closer look at Db2 Temporal Tables - they come with full SQL support (Time Travel SQL) - find details here
This is actually really simple if you have what's known as a Calendar table - a table with every date in it - although you can construct one on-the-fly if necessary. You can use it to turn this more obviously into a gaps-and-islands problem.
(You want one anyways, since they're one of the most useful analysis dimension tables):
SELECT valueA, valueB,
MIN(calendarDate) AS startDate,
MAX(calendarDate) + 1 DAY AS endDate
FROM (SELECT A.val AS valueA, B.val AS valueB, Calendar.calendarDate,
ROW_NUMBER() OVER(ORDER BY Calendar.calendarDate) -
ROW_NUMBER() OVER(PARTITION BY A.val, B.val ORDER BY Calendar.calendarDate) AS grouping
FROM Calendar
LEFT JOIN A
ON A.startDate <= Calendar.calendarDate
AND A.endDate > Calendar.calendarDate
LEFT JOIN B
ON B.startDate <= Calendar.calendarDate
AND B.endDate > Calendar.calendarDate
WHERE A.val IS NOT NULL
OR B.val IS NOT NULL) Groups
GROUP BY valueA, valueB, grouping
ORDER BY grouping
SQL Fiddle Example (Minor tweaks for SQL Server usage in example)
...which yields the following results. Note that there's a few extra days from the date range in table B that aren't present in table A!
valueA valueB startDate endDate
5 (null) 2018-01-01 2018-02-01
5 50 2018-02-01 2018-03-31
6 50 2018-03-31 2018-04-01
6 (null) 2018-04-01 2018-04-04
6 51 2018-04-04 2018-04-08
(null) 51 2018-04-08 2018-04-10
(This of course is trivially changeable by switching the join to A to a regular INNER JOIN, but I figured this and other cases would be important.)
I have following table
AssignmentID UserFrom UserTo GroupFrom GroupTo CreatedOn
201410 NULL 4327 103 103 2014/11/11 09:24.7
201549 NULL 4327 103 103 2014/11/11 09:32.4
201549 NULL 4327 103 103 2014/11/11 09:38.4
201673 NULL 4328 103 103 2014/12/11 09:56.1
201673 NULL 4328 103 103 2014/12/11 10:55.1
201673 NULL 4328 103 103 2014/12/11 10:59.1
I want to have datedifference in minutes vertically group by userto
in following way.Please give me suggestion to produce following output.
userto minutes
4327 8
4327 6
4328 55
4328 4
If you are using sqlserver 2008, you could use CROSS APPLY
Note this will not work well with duplicated CreatedOn within the same UserTo:
SELECT
t1.UserTo,
DateDiff(minute, 0, t1.CreatedOn - t2.previousCreatedOn) minutes
FROM yourtable t1
CROSS APPLY
(
SELECT
MAX(CreatedOn) previousCreatedOn
FROM yourtable
WHERE
t1.UserTo = UserTo
AND CreatedOn < t1.CreatedOn
HAVING
MAX(CreatedOn) is not null
) t2
If you are using sqlserver 2012 it is easy using LAG:
;WITH CTE AS
(
SELECT
userto,
datediff(minute, 0, createdon -lag(createdon) over
(partition by userto order by createdon)) minutes
FROM yourtable
)
SELECT userto, minutes
FROM CTE
WHERE minutes is not null
In SQL Server 2012+, you can use lag():
select userto, diff
from (select userto,
datediff(minute, lag(createdon) over (partition by userto order by createdon), createdon) as diff
from table t
) t
where diff is not null;
you can join the table to itself, with join conditions that only allow each row to join (match) the very next row for the same user in chronological sequence
Select a.userTo,
datediff(minute, a.createdOn, b.CreatedON) minutes
from table a
join table b
on b.userto = a.Userto
and b.createdon =
(Select Min(createdOn)
From table
Where userTo = a.UserTo
and createdOn > a.createdOn)
I have a table with the left 2 columns.
I am trying to achieve the 3th column based on some logic.
Logic: If we take date 1/1 and go further the highest score that wil be reached with going further in dates before the score goes down will be on 3/1. With a score of 12. So as HighestAchievedScore we will retrieve 12 for 1/1. And so forth.
If we are on a date where the next score goes down my highestAchieveScore will be my next score. Like you can see at 3/01/2014
date score HighestAchieveScore
1/01/2014 10 12
2/01/2014 11 12
3/01/2014 12 10
4/01/2014 10 11
5/01/2014 11 9
6/01/2014 9 8
7/01/2014 8 9
8/01/2014 9 9
I hope I explained it clear enough.
Thanks already for every input resolving the problem.
Lets make some test data:
DECLARE #Score TABLE
(
ScoreDate DATETIME,
Score INT
)
INSERT INTO #Score
VALUES
('01-01-2014', 10),
('01-02-2014', 11),
('01-03-2014', 12),
('01-04-2014', 10),
('01-05-2014', 11),
('01-06-2014', 9),
('01-07-2014', 8),
('01-08-2014', 9);
Now we are going to number our rows and then link to the next row to see if we are still going up
WITH ScoreRows AS
(
SELECT
s.ScoreDate,
s.Score,
ROW_NUMBER() OVER (ORDER BY ScoreDate) RN
FROM #Score s
),
ScoreUpDown AS
(
SELECT p.ScoreDate,
p.Score,
p.RN,
CASE WHEN p.Score < n.Score THEN 1 ELSE 0 END GoingUp,
ISNULL(n.Score, p.Score) NextScore
FROM ScoreRows p
LEFT JOIN ScoreRows n
ON n.RN = p.RN + 1
)
We take our data recursively look for the next row that is right before a fall, and take that value as our max for any row that is still going up. otherwise, we use the score for the next falling row.
SELECT
s.ScoreDate,
s.Score,
CASE WHEN s.GoingUp = 1 THEN d.Score ELSE s.NextScore END Test
FROM ScoreUpDown s
OUTER APPLY
(
SELECT TOP 1 * FROM ScoreUpDown d
WHERE d.ScoreDate > s.ScoreDate
AND GoingUp = 0
) d;
Output:
ScoreDate Score Test
2014-01-01 00:00:00.000 10 12
2014-01-02 00:00:00.000 11 12
2014-01-03 00:00:00.000 12 10
2014-01-04 00:00:00.000 10 11
2014-01-05 00:00:00.000 11 9
2014-01-06 00:00:00.000 9 8
2014-01-07 00:00:00.000 8 9
2014-01-08 00:00:00.000 9 9
Assuming you are wanting the third column to be computed, you can create the table like this (or add the column to an existing table), using a function to determine the value of the third column:
Create Function dbo.fnGetMaxScore(#Date Date)
Returns Int
As Begin
Declare #Ret Int
Select #Ret = Max(Score)
From YourTable
Where Date > #Date
Return #Ret
End
Create Table YourTable
(
Date Date,
Score Int,
HighestAchieveScore As dbo.fnGetMaxScore(Date)
)
I'm not sure this will work.... but this is the general concept.
Self join on A.Date < B.Date to get max score, but use coalesce and a 3rd self join on a rowID assigned in a CTE to determine if the score dropped on the next record, and if it did coalesce that score in, otherwise use the max score.
NEED TO TEST but have to setup a fiddle to do so..
WITH CTE as
(SELECT Date, Score, ROW_NUMBER() OVER(ORDER BY A.Date ASC) AS Row FROM tableName)
SELECT A.Date, A.Score, coalesce(c.score, Max(A.Score)) as HighestArchievedScore
FROM CTE A
LEFT JOIN CTE B
on A.Date < B.Date
LEFT JOIN CTE C
on A.Row+1=B.Row
and A.Score > C.Score
GROUP BY A.DATE,
A.SCORE
This should work on SQL Server 2012 but not earlier versions:
WITH cte AS (
SELECT date,
LEAD(score) OVER (ORDER BY date) nextScore
FROM yourTable
)
SELECT t.date, score,
CASE
WHEN nextScore < score THEN nextScore
ELSE (
SELECT ISNULL(MAX(t1.score), t.score)
FROM yourTable t1
JOIN cte ON t1.date = cte.date
WHERE t1.date > t.date
AND ISNULL(nextScore, 0) < score
)
END AS HighestAchieveScore
FROM yourTable t
JOIN cte ON t.date = cte.date
I have a table with many IDs and many dates associated with each ID, and even a few IDs with no date. For each ID and date combination, I want to select the ID, date, and the next largest date also associated with that same ID, or null as next date if none exists.
Sample Table:
ID Date
1 5/1/10
1 6/1/10
1 7/1/10
2 6/15/10
3 8/15/10
3 8/15/10
4 4/1/10
4 4/15/10
4
Desired Output:
ID Date Next_Date
1 5/1/10 6/1/10
1 6/1/10 7/1/10
1 7/1/10
2 6/15/10
3 8/15/10
3 8/15/10
4 4/1/10 4/15/10
4 4/15/10
SELECT
mytable.id,
mytable.date,
(
SELECT
MIN(mytablemin.date)
FROM mytable AS mytablemin
WHERE mytablemin.date > mytable.date
AND mytable.id = mytablemin.id
) AS NextDate
FROM mytable
This has been tested on SQL Server 2008 R2 (but it should work on other DBMSs) and produces the following output:
id date NextDate
----------- ----------------------- -----------------------
1 2010-05-01 00:00:00.000 2010-06-01 00:00:00.000
1 2010-06-01 00:00:00.000 2010-06-15 00:00:00.000
1 2010-07-01 00:00:00.000 2010-08-15 00:00:00.000
2 2010-06-15 00:00:00.000 2010-07-01 00:00:00.000
3 2010-08-15 00:00:00.000 NULL
3 2010-08-15 00:00:00.000 NULL
4 2010-04-01 00:00:00.000 2010-04-15 00:00:00.000
4 2010-04-15 00:00:00.000 2010-05-01 00:00:00.000
4 NULL NULL
Update 1:
For those that are interested, I've compared the performance of the two variants in SQL Server 2008 R2 (one uses MIN aggregate and the other uses TOP 1 with an ORDER BY):
Without an index on the date column, the MIN version had a cost of 0.0187916 and the TOP/ORDER BY version had a cost of 0.115073 so the MIN version was "better".
With an index on the date column, they performed identically.
Note that this was testing with just these 9 records so the results could be (very) spurious...
Update 2:
The results hold for 10,000 uniformly distributed random records. The TOP/ORDER BY query takes so long to run at 100,000 records I had to cancel it and give up.
If your db is oracle, you can use lead() and lag() functions.
SELECT id, date,
LEAD(date, 1, 0) OVER (PARTITION BY ID ORDER BY Date DESC NULLS LAST) NEXT_DATE,
FROM Your_table
ORDER BY ID;
SELECT
id,
date,
( SELECT date
FROM table t1
WHERE t1.date > t2.date
ORDER BY t1.date LIMIT 1 )
FROM table t2
I think self JOIN would be faster than subselect.
WITH dates AS (
SELECT 1 AS ID, '2010-05-01' AS Date
UNION ALL SELECT 1, '2010-06-01'
UNION ALL SELECT 1, '2010-07-01'
UNION ALL SELECT 2, '2010-06-15'
UNION ALL SELECT 3, '2010-08-15'
UNION ALL SELECT 3, '2010-08-15'
UNION ALL SELECT 4, '2010-04-01'
UNION ALL SELECT 4, '2010-04-15'
UNION ALL SELECT 4, ''
)
SELECT
dates.ID,
dates.Date,
nextDates.Date AS Next_Date
FROM
dates
LEFT JOIN
dates nextDates
ON nextDates.ID = dates.ID
AND nextDates.Date > dates.Date
LEFT JOIN
dates noLower
ON noLower.ID = nextDates.ID
AND noLower.Date < nextDates.Date
AND noLower.Date > dates.Date
WHERE
dates.Date > 0
AND noLower.ID IS NULL
https://www.db-fiddle.com/f/4sWRLt2hxjik5HqiJ21ez8/1