Count items in order next 12 months - sql-server

Question

I need to get Quantity of items in orders the next 12 months, like this:
ItemNumber
August 22
September 22
October 22
November 22
etc..
item1
10
13
12
130
..
item2
20
23
22
230
..
I can do like this for one month and repeat, but think there is a better way to do it.
SELECT I.ItemNumber, ThisMonth.Quantity AS This, NextMonth.Quantity AS Next *
FROM Items I
LEFT JOIN (
SELECT Quantity,Itemno
FROM [Orders]
WHERE MONTH([Shipment Date]) = MONTH(GETDATE()) AND YEAR([Shipment Date]) = YEAR(GETDATE())
) AS ThisMonth ON ThisMonth.Itemno = I.Itemnumber
LEFT JOIN (
SELECT Quantity,Itemno
FROM [Orders]
WHERE MONTH([Shipment Date]) = MONTH(DATEADD(month,+1,GETDATE())) AND YEAR([Shipment Date]) = YEAR(GETDATE())
) AS NextMonth ON NextMonth.Itemno = I.Itemnumber
Can you help? :)
UPDATED WITH MY TABLE DATA BELOW
ITEMS:
ItemNumber
item1
item2
ORDERS:
ItemNo
Shipment Date
Quantity
item1
2022-08-02
10
item1
2022-09-02
13
item1
2022-10-02
12
item1
2022-11-02
130
item2
2022-08-02
20
item3
2022-09-02
23
item4
2022-10-02
22
item5
2022-11-02
230

Answer 1

You haven't supplied sample data, but it looks like you need conditional aggregation (aka a pivot). It's generally easier, if a bit more verbose, to do this with SUM(CASE rather than using the PIVOT operator.
SELECT
i.ItemNumber,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE()) THEN i.Quantity END) AS CurrentMonth,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 1) THEN i.Quantity END) AS Month1,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 2) THEN i.Quantity END) AS Month2,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 3) THEN i.Quantity END) AS Month3,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 4) THEN i.Quantity END) AS Month4,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 5) THEN i.Quantity END) AS Month5,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 6) THEN i.Quantity END) AS Month6,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 7) THEN i.Quantity END) AS Month7,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 8) THEN i.Quantity END) AS Month8,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 9) THEN i.Quantity END) AS Month9,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 10) THEN i.Quantity END) AS Month10,
SUM(CASE WHEN EOMONTH(i.[Shipment Date]) = EOMONTH(GETDATE(), 11) THEN i.Quantity END) AS Month11,
FROM Items i
GROUP BY
i.ItemNumber;

Answer 2

A possible option, using the PIVOT relational operator:
Sample data:
SELECT *
INTO Items
FROM (VALUES
('item1', CONVERT(date, '20220802'), 10),
('item1', CONVERT(date, '20220902'), 13),
('item1', CONVERT(date, '20221002'), 12),
('item1', CONVERT(date, '20221102'), 130),
('item2', CONVERT(date, '20220802'), 20),
('item3', CONVERT(date, '20220902'), 23),
('item4', CONVERT(date, '20221002'), 22),
('item5', CONVERT(date, '20221102'), 230)
) t (ItemNo, ShipmentDate, Quantity)
Statement:
SELECT *
FROM (
SELECT ItemNo, Quantity, DATEDIFF(month, EOMONTH(GETDATE()), EOMONTH(ShipmentDate)) AS NextMonth
FROM Items
) t
PIVOT (
SUM(Quantity)
FOR NextMonth IN ([0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11])
) p
Result:
ItemNo
0
1
2
3
4
5
6
7
8
9
10
11
item1
10
13
12
130
item2
20
item3
23
item4
22
item5
230