How to calculate number of Orders for given date range - sql

Question

Need some help in writing sql query to capture number of active Orders between date range on month wise grouping. i.e if the user selected 2018-01-01 to 2019-12-31, I have to show number of active orders on a month basis i.e total 12 records.
I'm querying against Order Table whose schema looks like below
OrderID CustomerFirstName PurchaseDate OrderEndDate
1 XYZ 2018-01-01 9999-12-31
2 ABC 2018-02-02 2018-06-30
3 PQR 2018-06-01 2018-06-30
4 GHI 2018-01-01 2018-02-28
Order EndDate 9999-12-31 is never ending order.All considers has existing order in all date ranges.
From My UX, if I select Jan to Dec... Results should
JAN ==> 2 orders
Feb ==> 3 Orders => Order ID are 1,2,4.
Reason for Month FEB Order ID : 1,2,4 are consider as Active orders because
their end dates are falling in FEB.
For example : ORDER ID : 1 having End date has 9999-12-31 which is never ending. Always Active orders in all the date range
Order ID : 2 having End Date has 2018-06-30 so till June he should be considered has Active order for every Month
Order ID : 4 having end date has 2018-02-28 for Feb month OrderID is active Orders
Expected Output
Month NoOfOrders
Jan 2
Feb 3
Month NoOfOrder
Jan 2
Feb 3

Answer 1

Create a year-month table (inspired from this answer) and join the Order table against it
DECLARE #DateFrom datetime, #DateTo Datetime
SET #DateFrom = ' 2018-01-01'
SET #DateTo = '2018-12-31'
SELECT YearMonth, COUNT(*)
FROM (SELECT CONVERT(CHAR(4),DATEADD(MONTH, x.number, #DateFrom),120) + '-' + CONVERT(CHAR(2),DATEADD(MONTH, x.number, #DateFrom),110) As YearMonth,
CONVERT(DATE, CONVERT(CHAR(4),DATEADD(MONTH, x.number, #DateFrom),120) + '-' + Convert(CHAR(2),DATEADD(MONTH, x.number, #DateFrom),110) + '-01', 23) fulldate
FROM master.dbo.spt_values x
WHERE x.type = 'P'
AND x.number <= DATEDIFF(MONTH, #DateFrom, #DateTo)) YearMonthTbl
LEFT JOIN Orders o ON YEAR(fulldate) >= YEAR(purchaseDate) AND MONTH(fulldate) >= MONTH(purchaseDate) and fulldate < = enddate
GROUP BY YearMonth
I decided to include also year in output if the input range crosses into a new year
Here is the output for completeness
2018-01 2
2018-02 3
2018-03 2
2018-04 2
2018-05 2
2018-06 3
2018-07 1
2018-08 1
2018-09 1
2018-10 1
2018-11 1
2018-12 1

Answer 2

First Part - Handling records with orderenddate= '9999-12-31'
You can try like following. By putting a OR condition for orderenddate = '9999-12-31' will make sure that never ending records will eppear in all the searchs if the strat date is within the boundary.
SELECT *
FROM [order]
WHERE purchasedate >= #startdate
AND ( orderenddate <= #enddate
OR orderenddate = '9999-12-31' )
Second Part :
sql query to capture number of active Orders between date range on
month wise grouping.
For month wise grouping you can try like following.
;WITH numbersequence( number )
AS (SELECT 1 AS Number
UNION ALL
SELECT number + 1
FROM numbersequence
WHERE number < 12)
SELECT Sum(ct) ActiveOrderCount,
number AS [month]
FROM (SELECT number,
CASE
WHEN c.number >= Month(purchasedate)
AND c.number <= Month(orderenddate) THEN 1
ELSE 0
END ct
FROM #order
CROSS JOIN numbersequence c
WHERE purchasedate >= #startdate
AND ( orderenddate <= #enddate
OR orderenddate = '9999-12-31' )) t
GROUP BY number
Online Demo
Output
+------------------+-------+
| ActiveOrderCount | Month |
+------------------+-------+
| 2 | 1 |
+------------------+-------+
| 3 | 2 |
+------------------+-------+
| 2 | 3 |
+------------------+-------+
| 2 | 4 |
+------------------+-------+
| 2 | 5 |
+------------------+-------+
| 3 | 6 |
+------------------+-------+
| 1 | 7 |
+------------------+-------+
| 1 | 8 |
+------------------+-------+
| 1 | 9 |
+------------------+-------+
| 1 | 10 |
+------------------+-------+
| 1 | 11 |
+------------------+-------+
| 1 | 12 |
+------------------+-------+
Assumption : Start Date and End Date falls under same year. Otherwise you need to put year condition also.