Fill up date gap by month - sql

Question

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.

Answer 1

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.

Answer 2

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.

Answer 3

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

Answer 4

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

Answer 5

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