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I have a table
DATE Val
01-01-2020 1
01-02-2020 3
01-05-2020 2
01-07-2020 8
01-13-2020 3
...
I want to summarize these values by the following Sunday. For example, in the above example:
1-05-2020, 1-12-2020, and 1-19-2020 are Sundays, so I want to summarize these by those dates.
The final result should be something like
DATE SUM
1-05-2020 6 //(01-01-2020 + 01-02-2020 + 01-05-2020)
1-12-2020 8
1-19-2020 3
I wasn't certain if the best place to start would be to create a temp calendar table, and then try to join backwards based on that? Or if there was an easier way involving DATEDIFF. Any help would be appreciated! Thanks!
Here's a solution that uses DATEADD & DATEPART to calculate the closest Sunday.
With a correction for a different setting of ##datefirst.
(Since the datepart weekday values are different depending on the DATEFIRST setting)
Sample data:
create table #TestTable
(
Id int identity(1,1) primary key,
[Date] date,
Val int
);
insert into #TestTable
([Date], Val)
VALUES
('2020-01-01', 1)
, ('2020-01-02', 3)
, ('2020-01-05', 2)
, ('2020-01-07', 8)
, ('2020-01-13', 3)
;
Query:
WITH CTE_DATA AS
(
SELECT [Date], Val
, DATEADD(day,
((7-(##datefirst+datepart(weekday, [Date])-1)%7)%7),
[Date]) AS Sunday
FROM #TestTable
)
SELECT
Sunday AS [Date],
SUM(Val) AS [Sum]
FROM CTE_DATA
GROUP BY Sunday
ORDER BY Sunday;
Date | Sum
:--------- | --:
2020-01-05 | 6
2020-01-12 | 8
2020-01-19 | 3
db<>fiddle here
Extra:
Apparently the trick of adding the difference of weeks from day 0 to day 6 also works independently from the DATEFIRST setting.
So this query will return the same result for the sample data.
WITH CTE_DATA AS
(
SELECT [Date], Val
, CAST(DATEADD(week, DATEDIFF(week, 0, DATEADD(day, -1, [Date])), 6) AS DATE) AS Sunday
FROM #TestTable
)
SELECT
Sunday AS [Date],
SUM(Val) AS [Sum]
FROM CTE_DATA
GROUP BY Sunday
ORDER BY Sunday;
The subtraction of 1 day makes sure that if the date is already a Sunday that it isn't calculated to the next Sunday.
Here is a way to do it:
nb:1-13-2020 wont show cuz its not a sunday
with cte as
(
select cast('01-01-2020'as Date) as Date, 1 as Val
union select '01-02-2020' , 3
union select '01-05-2020' , 2
union select '01-07-2020' , 8
)
select Date, max(dateadd(dd,number,Date)), sum(distinct Val) as SUM
from master..spt_values a inner join cte on Date <= dateadd(dd,number,Date)
where type = 'p'
and year(dateadd(dd,number,Date))=year(Date)
and DATEPART(dw,dateadd(dd,number,Date)) = 7
group by Date
Output:
Date (No column name) SUM
2020-01-01 2020-12-26 1
2020-01-02 2020-12-26 3
2020-01-05 2020-12-26 2
2020-01-07 2020-12-26 8
Here is a simple solution. Putting your values into a temporary table and viewing the results on that table:
DECLARE #dates TABLE
(
mDATE DATE,
Val INT,
Sunday DATE
)
INSERT INTO #dates (mDATE,Val) VALUES
('01-01-2020',1),('01-02-2020',3),('01-05-2020',2),('01-07-2020',8),('01-13-2020',3)
UPDATE #dates
SET Sunday = dateadd(week, datediff(week, 0, mDATE), 6)
SELECT Sunday,SUM(Val) AS Val FROM #dates
GROUP BY Sunday
OUTPUT:
Sunday Val
2020-01-05 4
2020-01-12 10
2020-01-19 3
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
My data looks something like this
ProductNumber | YearMonth | Number
1 201803 1
1 201804 3
1 201810 6
2 201807 -3
2 201809 5
Now what I want to have is add an additional entry "6MSum" which is the sum of the last 6 months per ProductNumber (not the last 6 entries).
Please be aware the YearMonth data is not complete, for every ProductNumber there are gaps in between so I cant just use the last 6 entries for the sum. The final result should look something like this.
ProductNumber | YearMonth | Number | 6MSum
1 201803 1 1
1 201804 3 4
1 201810 6 9
2 201807 -3 -3
2 201809 5 2
Additionally I don't want to insert the sum to the table but instead use it in a query like:
SELECT [ProductNumber],[YearMonth],[Number],
6MSum = CONVERT(INT,SUM...)
FROM ...
I found a lot off solutions that use a "sum over period" but only for the last X entries and not for the actual conditional statement of "YearMonth within last 6 months".
Any help would be much appreciated!
Its a SQL Database
EDIT/Answer
It seems to be the case that the gaps within the months have to be filled with data, afterwards something like
sum(Number) OVER (PARTITION BY category
ORDER BY year, week
ROWS 6 PRECEDING) AS 6MSum
Should work.
Reference to the solution : https://dba.stackexchange.com/questions/181773/sum-of-previous-n-number-of-columns-based-on-some-category
You could go the OUTER APPLY route. The following produces your required results exactly:
-- prep data
SELECT
ProductNumber , YearMonth , Number
into #t
FROM ( values
(1, 201803 , 1 ),
(1, 201804 , 3 ),
(1, 201810 , 6 ),
(2, 201807 , -3 ),
(2, 201809 , 5 )
) s (ProductNumber , YearMonth , Number)
-- output
SELECT
ProductNumber
,YearMonth
,Number
,[6MSum]
FROM #t t
outer apply (
SELECT
sum(number) as [6MSum]
FROM #t it
where
it.ProductNumber = t.ProductNumber
and it.yearmonth <= t.yearmonth
and t.yearmonth - it.yearmonth between 0 and 6
) tt
drop table #t
Use outer apply and convert yearmonth to a date, something like this:
with t as (
select t.*,
convert(date, convert(varchar(255), yearmonth) + '01')) as ymd
from yourtable t
)
select t.*, t2.sum_6m
from t outer apply
(select sum(t2.number) as sum_6m
from t t2
where t2.productnumber = t.productnumber and
t2.ymd <= t.ymd and
t2.ymd > dateadd(month, -6, ymd)
) t2;
Just to provide one more option. You can use DATEFROMPARTS to build valid dates from the YearMonth value and then search for values within date ranges.
Testable here: https://rextester.com/APJJ99843
SELECT
ProductNumber , YearMonth , Number
INTO #t
FROM ( values
(1, 201803 , 1 ),
(1, 201804 , 3 ),
(1, 201810 , 6 ),
(2, 201807 , -3 ),
(2, 201809 , 5 )
) s (ProductNumber , YearMonth , Number)
SELECT *
,[6MSum] = (SELECT SUM(number) FROM #t WHERE
ProductNumber = t.ProductNumber
AND DATEFROMPARTS(LEFT(YearMonth,4),RIGHT(YearMonth,2),1) --Build a valid start of month date
BETWEEN
DATEADD(MONTH,-6,DATEFROMPARTS(LEFT(t.YearMonth,4),RIGHT(t.YearMonth,2),1)) --Build a valid start of month date 6 months back
AND DATEFROMPARTS(LEFT(t.YearMonth,4),RIGHT(t.YearMonth,2),1)) --Build a valid end of month date
FROM #t t
DROP TABLE #t
So a working query (provided by a colleauge of mine) can look like this
SELECT [YearMonth]
,[Number]
,[ProductNumber]
, (Select Sum(Number) from [...] DPDS_1 where DPDS.ProductNumber =
DPDS_1.ProductNumber and DPDS_1.YearMonth <= DPDS.YearMonth and DPDS_1.YearMonth >=
convert (int, left (convert (varchar, dateadd(mm, -6, DPDS.YearMonth + '01'), 112),
6)))FROM [...] DPDS
I'm struggling with this for a few days... trying to write an SQL query to get all date ranges when all units overlap at the same time. It's better to see it graphically.
Here is the simplified table with the image for reference:
UnitId Start End
====== ========== ==========
1 05/01/2018 09/01/2018
1 10/01/2018 13/01/2018
2 04/01/2018 15/01/2018
2 19/01/2018 23/01/2018
3 06/01/2018 12/01/2018
3 14/01/2018 22/01/2018
Expected result:
Start End
====== ==========
06/01/2018 09/01/2018
10/01/2018 12/01/2018
What I currently have:
DECLARE #sourceTable TABLE (UnitId int, StartDate datetime, EndDate datetime);
INSERT INTO #sourceTable VALUES
(1, '2018-01-05', '2018-01-09')
,(1, '2018-01-10', '2018-01-13')
,(2, '2018-01-04', '2018-01-15')
,(2, '2018-01-19', '2018-01-23')
,(3, '2018-01-06', '2018-01-12')
,(3, '2018-01-14', '2018-01-22');
SELECT DISTINCT
(SELECT max(v) FROM (values(A.StartDate), (B.StartDate)) as value(v)) StartDate
,(SELECT min(v) FROM (values(A.EndDate), (B.EndDate)) as value(v)) EndDate
FROM #sourceTable A
JOIN #sourceTable B
ON A.startDate <= B.endDate AND A.endDate >= B.startDate AND A.UnitId != B.UnitId
I believe it is "count number of overlapping intervals" problem (this picture should help). Here is one solution to it:
DECLARE #t TABLE (UnitId INT, [Start] DATE, [End] DATE);
INSERT INTO #t VALUES
(1, '2018-01-05', '2018-01-09'),
(1, '2018-01-10', '2018-01-13'),
(2, '2018-01-04', '2018-01-15'),
(2, '2018-01-19', '2018-01-23'),
(3, '2018-01-06', '2018-01-12'),
(3, '2018-01-14', '2018-01-22');
WITH cte1(date, val) AS (
SELECT [Start], 1 FROM #t AS t
UNION ALL
SELECT [End], 0 FROM #t AS t
UNION ALL
SELECT DATEADD(DAY, 1, [End]), -1 FROM #t AS t
), cte2 AS (
SELECT date, SUM(val) OVER (ORDER BY date, val) AS usage
FROM cte1
)
SELECT date, MAX(usage) AS usage
FROM cte2
GROUP BY date
It will give you a list of all dates at which the use count (possibly) changed:
date usage
2018-01-04 1
2018-01-05 2
2018-01-06 3
2018-01-09 3
2018-01-10 3
2018-01-12 3
2018-01-13 2
2018-01-14 2
2018-01-15 2
2018-01-16 1
2018-01-19 2
2018-01-22 2
2018-01-23 1
2018-01-24 0
With this approach you do not need a calendar table or rCTE to build missing dates. Converting the above to ranges (2018-01-05 ... 2018-01-15, 2018-01-19 ... 2018-01-22 etc) is not very difficult.
DECLARE #t TABLE (UnitId INT, [Start] DATE, [End] DATE);
INSERT INTO #t VALUES
(1, '2018-01-05', '2018-01-09'),
(1, '2018-01-10', '2018-01-13'),
(2, '2018-01-04', '2018-01-15'),
(2, '2018-01-19', '2018-01-23'),
(3, '2018-01-06', '2018-01-12'),
(3, '2018-01-14', '2018-01-22');
WITH cte1(date, val) AS (
SELECT [Start], 1 FROM #t AS t -- starting date increments counter
UNION ALL
SELECT [End], 0 FROM #t AS t -- we need all edges in the result
UNION ALL
SELECT DATEADD(DAY, 1, [End]), -1 FROM #t AS t -- end date + 1 decrements counter
), cte2 AS (
SELECT date, SUM(val) OVER (ORDER BY date, val) AS usage -- running sum for counter
FROM cte1
), cte3 AS (
SELECT date, MAX(usage) AS usage -- group multiple events on same date together
FROM cte2
GROUP BY date
), cte4 AS (
SELECT date, usage, CASE
WHEN usage > 1 AND LAG(usage) OVER (ORDER BY date) > 1 THEN 0
WHEN usage < 2 AND LAG(usage) OVER (ORDER BY date) < 2 THEN 0
ELSE 1
END AS chg -- start new group if prev and curr usage are on opposite side of 1
FROM cte3
), cte5 AS (
SELECT date, usage, SUM(chg) OVER (ORDER BY date) AS grp -- number groups for each change
FROM cte4
)
SELECT MIN(date) date1, MAX(date) date2
FROM cte5
GROUP BY grp
HAVING MIN(usage) > 1
Result:
date1 date2
2018-01-05 2018-01-15
2018-01-19 2018-01-22
You are looking for date ranges where all units overlap. So look for start dates where all units exist and end dates where all units exist and then join the two.
I'm using ROW_NUMBER to join the first start date with the first end date, the second start date with the second end date and so on.
select s.startdate, e.enddate
from
(
select startdate, row_number() over (order by startdate) as rn
from #sourceTable s1
where
(
select count(*)
from #sourceTable s2
where s1.startdate between s2.startdate and s2.enddate
) = (select count(distinct unitid) from #sourceTable)
) s
join
(
select enddate, row_number() over (order by startdate) as rn
from #sourceTable s1
where
(
select count(*)
from #sourceTable s2
where s1.enddate between s2.startdate and s2.enddate
) = (select count(distinct unitid) from #sourceTable)
) e on e.rn = s.rn
order by s.startdate;
There may be more elegant ways to solve this, but I guess this query is at least easy to understand :-)
Rextester demo: https://rextester.com/GRRSW89045
I am using SQL Server 2008 and am trying to increase the speed of my query below. The query assigns points to patients based on readmission dates.
Example: A patient is seen on 1/2, 1/5, 1/7, 1/8, 1/9, 2/4. I want to first group visits within 3 days of each other. 1/2-5 are grouped, 1/7-9 are grouped. 1/5 is NOT grouped with 1/7 because 1/5's actual visit date is 1/2. 1/7 would receive 3 points because it is a readmit from 1/2. 2/4 would also receive 3 points because it is a readmit from 1/7. When the dates are grouped the first date is the actual visit date.
Most articles suggest limiting the data set or adding indexes to increase speed. I have limited the amount of rows to about 15,000 and added a index. When running the query with 45 test visit dates/ 3 test patients, the query takes 1.5 min to run. With my actual data set it takes > 8 hrs.
How can I get this query to run < 1 hr? Is there a better way to write my query? Does my Index look correct? Any help would be greatly appreciated.
Example expected results below query.
;CREATE TABLE RiskReadmits(MRN INT, VisitDate DATE, Category VARCHAR(15))
;CREATE CLUSTERED INDEX Risk_Readmits_Index ON RiskReadmits(VisitDate)
;INSERT RiskReadmits(MRN,VisitDate,CATEGORY)
VALUES
(1, '1/2/2016','Inpatient'),
(1, '1/5/2016','Inpatient'),
(1, '1/7/2016','Inpatient'),
(1, '1/8/2016','Inpatient'),
(1, '1/9/2016','Inpatient'),
(1, '2/4/2016','Inpatient'),
(1, '6/2/2016','Inpatient'),
(1, '6/3/2016','Inpatient'),
(1, '6/5/2016','Inpatient'),
(1, '6/6/2016','Inpatient'),
(1, '6/8/2016','Inpatient'),
(1, '7/1/2016','Inpatient'),
(1, '8/1/2016','Inpatient'),
(1, '8/4/2016','Inpatient'),
(1, '8/15/2016','Inpatient'),
(1, '8/18/2016','Inpatient'),
(1, '8/28/2016','Inpatient'),
(1, '10/12/2016','Inpatient'),
(1, '10/15/2016','Inpatient'),
(1, '11/17/2016','Inpatient'),
(1, '12/20/2016','Inpatient')
;WITH a AS (
SELECT
z1.VisitDate
, z1.MRN
, (SELECT MIN(VisitDate) FROM RiskReadmits WHERE VisitDate > DATEADD(day, 3, z1.VisitDate)) AS NextDay
FROM
RiskReadmits z1
WHERE
CATEGORY = 'Inpatient'
), a1 AS (
SELECT
MRN
, MIN(VisitDate) AS VisitDate
, MIN(NextDay) AS NextDay
FROM
a
GROUP BY
MRN
), b AS (
SELECT
VisitDate
, MRN
, NextDay
, 1 AS OrderRow
FROM
a1
UNION ALL
SELECT
a.VisitDate
, a.MRN
, a.NextDay
, b.OrderRow +1 AS OrderRow
FROM
a
JOIN b
ON a.VisitDate = b.NextDay
), c AS (
SELECT
MRN,
VisitDate
, (SELECT MAX(VisitDate) FROM b WHERE b1.VisitDate > VisitDate AND b.MRN = b1.MRN) AS PreviousVisitDate
FROM
b b1
)
SELECT distinct
c1.MRN,
c1.VisitDate
, CASE
WHEN DATEDIFF(day,c1.PreviousVisitDate,c1.VisitDate) < 30 THEN PreviousVisitDate
ELSE NULL
END AS ReAdmissionFrom
, CASE
WHEN DATEDIFF(day,c1.PreviousVisitDate,c1.VisitDate) < 30 THEN 3
ELSE 0
END AS Points
FROM
c c1
ORDER BY c1.MRN
Expected Results:
MRN VisitDate ReAdmissionFrom Points
1 2016-01-02 NULL 0
1 2016-01-07 2016-01-02 3
1 2016-02-04 2016-01-07 3
1 2016-06-02 NULL 0
1 2016-06-06 2016-06-02 3
1 2016-07-01 2016-06-06 3
1 2016-08-01 NULL 0
1 2016-08-15 2016-08-01 3
1 2016-08-28 2016-08-15 3
1 2016-10-12 NULL 0
1 2016-11-17 NULL 0
1 2016-12-20 NULL 0
oops I changed the names of a few cte's (and the post messed up what was code)
It should be like this:
b AS (
SELECT
VisitDate
, MRN
, NextDay
, 1 AS OrderRow
FROM
a1
UNION ALL
SELECT
a.VisitDate
, a.MRN
, a.NextDay
, b.OrderRow +1 AS OrderRow
FROM
a AS a
JOIN b
ON a.VisitDate = b.NextDay AND a.MRN = b.MRN
)
I'm going to take a wild guess here and say you want to change the b cte to
have AND a.MRN = b.MRN as a second condition in the second select query like this:
, b AS (
SELECT
VisitDate
, MRN
, NextDay
, 1 AS OrderRow
FROM
firstVisitAndFollowUp
UNION ALL
SELECT
a.VisitDate
, a.MRN
, a.NextDay
, b.OrderRow +1 AS OrderRow
FROM
visitsDistance3daysOrMore AS a
JOIN b
ON a.VisitDate = b.NextDay AND a.MRN = b.MRN
)