SQL Server 2022

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CREATE TABLE SomeTable
(
    SomeYRMTH CHAR(6) NOT NULL PRIMARY KEY
  , SomeNumber INTEGER NOT NULL
);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202201', 20);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202204', 53);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202205', 2);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202206', 81);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202207', 7);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202209', 78);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202210', 57);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202211', 90);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202212', 36);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202301', 62);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202302', 8);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202303', 57);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202304', 50);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202305', 50);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202306', 56);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202307', 80);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202308', 28);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202309', 48);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202310', 92);
INSERT INTO SomeTable (SomeYRMTH, SomeNumber) VALUES ('202311', 54);

DECLARE @START_DATE DATETIME;
DECLARE @END_DATE DATETIME;
SET @START_DATE = '2022-01-01';
SET @END_DATE = '2023-12-31';

;WITH cte_dates AS
(
    SELECT @START_DATE DateValue
    UNION ALL
    SELECT DATEADD (DAY, 1, DateValue)
    FROM   cte_dates
    WHERE  DATEADD (DAY, 1, DateValue) <= @END_DATE
)
SELECT * FROM (
SELECT
          cal.YRMTH
        , tmp.SomeYRMTH
        , tmp.SomeNumber
        , SUM (tmp.SomeNumber) OVER (ORDER BY cal.YRMTH
                                     ROWS BETWEEN 13 PRECEDING AND 1 PRECEDING
                                    ) AS [MovingSum]
FROM      (
              SELECT
                    CONVERT (CHAR(4), YEAR (cte_dates.DateValue))
                    + RIGHT('0' + CONVERT (VARCHAR(2), MONTH (cte_dates.DateValue)), 2) AS [YRMTH]
              FROM  cte_dates
              WHERE DAY (cte_dates.DateValue) = 1
          )          cal
LEFT JOIN SomeTable tmp ON cal.YRMTH = tmp.SomeYRMTH) x
WHERE x.SomeYRMTH IS NOT NULL
OPTION (MAXRECURSION 32767);

YRMTH	SomeYRMTH	SomeNumber	MovingSum
202201	202201	20	null
202204	202204	53	20
202205	202205	2	73
202206	202206	81	75
202207	202207	7	156
202209	202209	78	163
202210	202210	57	241
202211	202211	90	298
202212	202212	36	388
202301	202301	62	424
202302	202302	8	486
202303	202303	57	474
202304	202304	50	531
202305	202305	50	581
202306	202306	56	578
202307	202307	80	632
202308	202308	28	631
202309	202309	48	652
202310	202310	92	700
202311	202311	54	714

Warning: Null value is eliminated by an aggregate or other SET operation.