SQL - Display Months as columns - sql-server

Question

I have a SQL Server table that has Start (1-1-2017) and End (1-1-2022) dates for contracts with invoices being generated each month for current and past months.
I would like to display months as columns even when no invoice has been generated, is that possible with just SQL / Pivot tables or a table with dates as calendar must be created?
I have worked with this code so far.
WITH CTE_MyTable AS
(
SELECT
FORMAT(MIN(StartDate), 'yyyy-MM') AS [MyDate]
FROM
MyTable
UNION ALL
SELECT
FORMAT(MIN(DATEADD(month, 1, StartDate)), 'yyyy-MM') AS [MyDate]
FROM
MyTable
WHERE
FORMAT(DATEADD(month, 1, StartDate),'yyyy-MM') <= (SELECT FORMAT(MAX(EndDate), 'yyyy-MM') AS [MyDate] FROM MyTable)
)
SELECT [MyDate]
FROM CTE_ MyTable
GROUP BY MyDate
OPTION (MAXRECURSION 0);

Answer 1

So let's say your table looked like this (using temp variable so you can just copy/paste/test):
DECLARE #sale TABLE(saledate DATE, saleamt MONEY);
INSERT #sale VALUES ('20170103',500),('20170128',266),('20170303',4002),('20170409',25);
Note that I'm only doing 6 months for simplicity. The following query get the count of sales per month (first query) and the sum of the sales for the second query:
DECLARE #sale TABLE(saledate DATE, saleamt MONEY);
INSERT #sale VALUES ('20170103',500),('20170128',266),('20170303',4002),('20170409',25);
SELECT
[201701] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 1 THEN 1 END),
[201702] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 2 THEN 1 END),
[201703] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 3 THEN 1 END),
[201704] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 4 THEN 1 END),
[201705] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 5 THEN 1 END),
[201706] = COUNT(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 6 THEN 1 END)
FROM #sale t;
SELECT
[201701] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 1 THEN t.saleamt END),0),
[201702] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 2 THEN t.saleamt END),0),
[201703] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 3 THEN t.saleamt END),0),
[201704] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 4 THEN t.saleamt END),0),
[201705] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 5 THEN t.saleamt END),0),
[201706] = ISNULL(SUM(CASE WHEN YEAR(t.saledate)=2017 AND MONTH(t.saledate) = 6 THEN t.saleamt END),0)
FROM #sale t;
These queries return:
201701 201702 201703 201704 201705 201706
----------- ----------- ----------- ----------- ----------- -----------
2 0 1 1 0 0
201701 201702 201703 201704 201705 201706
--------------------- --------------------- --------------------- --------------------- --------------------- ---------------------
766.00 0.00 4002.00 25.00 0.00 0.00

Answer 2

There is a way to pivot columns in SQL- using the Pivot() function (Microsoft Documentation at: https://learn.microsoft.com/en-us/sql/t-sql/queries/from-using-pivot-and-unpivot?view=sql-server-2017)
To display months as columns (1 to 12) the Pivot() function assigns values to (hard-coded) columns. Implemented correctly, there are NULLS where the aggregation doesn't occur due to lack of records. The implied way to replace NULLS with zeroes is by using the COALESCE() function.
The year values of the pivoted data should be grouped and while there is no specific Group By for a pivot, this is implied by how the SourceTable query is written.
In this example code I use the same exact format as the official documentation; with the exception that I additionally group by year and COALESCE NULLs with 0's.
What I am doing is counting the number of records for a given month and year:
SELECT yearval
,COALESCE([1], 0) [Jan]
,COALESCE([2], 0) [Feb]
,COALESCE([3], 0) [Mar]
,COALESCE([4], 0) [Apr]
,COALESCE([5], 0) [May]
,COALESCE([6], 0) [Jun]
,COALESCE([7], 0) [Jul]
,COALESCE([8], 0) [Aug]
,COALESCE([9], 0) [Sep]
,COALESCE([10], 0) [Oct]
,COALESCE([11], 0) [Nov]
,COALESCE([12], 0) [Dec]
FROM
(SELECT YEAR([Your_Date_Column_Here]) AS [yearval]
,MONTH([Your_Date_Column_Here]) AS [monthval]
FROM [Your_Table_Name_Here]) AS SourceTable
PIVOT
(
COUNT(monthval) FOR monthval IN ([1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12])
) AS PivotTable
Would produce this output in my test database:
yearval Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2015 1952 1122 1678 2364 1125 1308 1414 2103 1031 1340 2506 1015
2016 1123 1413 1568 1421 1278 1252 1048 1290 1251 1571 2647 1253
2017 0 0 0 3 0 1241 2377 2714 6724 1388 1521 1243
2018 2127 2118 2449 2330 2687 3833 3279 883 0 0 0 0