Oracle 18c

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CREATE TABLE table_name ( Month, site, channel, type, revenue ) AS
SELECT DATE '2017-02-01', 'abc', 1, 'A',  50 FROM DUAL UNION ALL
SELECT DATE '2017-04-01', 'abc', 2, 'B', 100 FROM DUAL UNION ALL
SELECT DATE '2018-12-01', 'xyz', 1, 'A', 150 FROM DUAL;
3 rows affected

ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
SELECT ADD_MONTHS( t.year, c.month - 1 ) AS month,
       t.site,
       t.channel,
       t.type,
       SUM( COALESCE( t.revenue, 0 ) ) OVER (
         PARTITION BY t.site, t.channel, t.type, t.year
         ORDER BY c.month
       ) AS ytd_revenue
FROM   (
         SELECT LEVEL AS month
         FROM   DUAL
         CONNECT BY LEVEL <= 12
       ) c
       LEFT OUTER JOIN (
         SELECT t.*,
                TRUNC( month, 'YY' ) AS year
         FROM   table_name t
       ) t
       PARTITION BY ( site, channel, type, year )
       ON ( c.month = EXTRACT( MONTH FROM t.month ) );


MONTH
SITE
CHANNEL
TYPE
YTD_REVENUE


2017-01-01 00:00:00
abc
1
A
0

2017-02-01 00:00:00
abc
1
A
50

2017-03-01 00:00:00
abc
1
A
50

2017-04-01 00:00:00
abc
1
A
50

2017-05-01 00:00:00
abc
1
A
50

2017-06-01 00:00:00
abc
1
A
50

2017-07-01 00:00:00
abc
1
A
50

2017-08-01 00:00:00
abc
1
A
50

2017-09-01 00:00:00
abc
1
A
50

2017-10-01 00:00:00
abc
1
A
50

2017-11-01 00:00:00
abc
1
A
50

2017-12-01 00:00:00
abc
1
A
50

2017-01-01 00:00:00
abc
2
B
0

2017-02-01 00:00:00
abc
2
B
0

2017-03-01 00:00:00
abc
2
B
0

2017-04-01 00:00:00
abc
2
B
100

2017-05-01 00:00:00
abc
2
B
100

2017-06-01 00:00:00
abc
2
B
100

2017-07-01 00:00:00
abc
2
B
100

2017-08-01 00:00:00
abc
2
B
100

2017-09-01 00:00:00
abc
2
B
100

2017-10-01 00:00:00
abc
2
B
100

2017-11-01 00:00:00
abc
2
B
100

2017-12-01 00:00:00
abc
2
B
100

2018-01-01 00:00:00
xyz
1
A
0

2018-02-01 00:00:00
xyz
1
A
0

2018-03-01 00:00:00
xyz
1
A
0

2018-04-01 00:00:00
xyz
1
A
0

2018-05-01 00:00:00
xyz
1
A
0

2018-06-01 00:00:00
xyz
1
A
0

2018-07-01 00:00:00
xyz
1
A
0

2018-08-01 00:00:00
xyz
1
A
0

2018-09-01 00:00:00
xyz
1
A
0

2018-10-01 00:00:00
xyz
1
A
0

2018-11-01 00:00:00
xyz
1
A
0

2018-12-01 00:00:00
xyz
1
A
150


WITH calendar ( month ) AS (
  SELECT ADD_MONTHS( start_month, LEVEL - 1 )
  FROM   (
    SELECT MIN( TRUNC( ADD_MONTHS( month, -3 ), 'YY' ) ) AS start_month,
           ADD_MONTHS( MAX( TRUNC( ADD_MONTHS( month, -3 ), 'YY' ) ), 11 ) AS end_month
    FROM   table_name
  )
  CONNECT BY
          ADD_MONTHS( start_month, LEVEL - 1 ) <= end_month
)
SELECT TO_CHAR( ADD_MONTHS( c.month, 3 ), 'YYYY-MM' ) AS month,
       t.site,
       t.channel,
       t.type,
       SUM( COALESCE( t.revenue, 0 ) ) OVER (
         PARTITION BY t.site, t.channel, t.type, TRUNC( c.month, 'YY' )
         ORDER BY c.month
       ) AS ytd_revenue
FROM   calendar c
       LEFT OUTER JOIN (
         SELECT ADD_MONTHS( month, -3 ) AS month,
                site,
                channel,
                type,
                revenue,
                TRUNC( ADD_MONTHS( month, -3 ), 'YY' ) AS year
         FROM   table_name t
       ) t
       PARTITION BY ( site, channel, type )
       ON ( c.month = t.month )
ORDER BY
       site, channel, type, month;


MONTH
SITE
CHANNEL
TYPE
YTD_REVENUE


2016-04
abc
1
A
0

2016-05
abc
1
A
0

2016-06
abc
1
A
0

2016-07
abc
1
A
0

2016-08
abc
1
A
0

2016-09
abc
1
A
0

2016-10
abc
1
A
0

2016-11
abc
1
A
0

2016-12
abc
1
A
0

2017-01
abc
1
A
0

2017-02
abc
1
A
50

2017-03
abc
1
A
50

2017-04
abc
1
A
0

2017-05
abc
1
A
0

2017-06
abc
1
A
0

2017-07
abc
1
A
0

2017-08
abc
1
A
0

2017-09
abc
1
A
0

2017-10
abc
1
A
0

2017-11
abc
1
A
0

2017-12
abc
1
A
0

2018-01
abc
1
A
0

2018-02
abc
1
A
0

2018-03
abc
1
A
0

2018-04
abc
1
A
0

2018-05
abc
1
A
0

2018-06
abc
1
A
0

2018-07
abc
1
A
0

2018-08
abc
1
A
0

2018-09
abc
1
A
0

2018-10
abc
1
A
0

2018-11
abc
1
A
0

2018-12
abc
1
A
0

2019-01
abc
1
A
0

2019-02
abc
1
A
0

2019-03
abc
1
A
0

2016-04
abc
2
B
0

2016-05
abc
2
B
0

2016-06
abc
2
B
0

2016-07
abc
2
B
0

2016-08
abc
2
B
0

2016-09
abc
2
B
0

2016-10
abc
2
B
0

2016-11
abc
2
B
0

2016-12
abc
2
B
0

2017-01
abc
2
B
0

2017-02
abc
2
B
0

2017-03
abc
2
B
0

2017-04
abc
2
B
100

2017-05
abc
2
B
100

2017-06
abc
2
B
100

2017-07
abc
2
B
100

2017-08
abc
2
B
100

2017-09
abc
2
B
100

2017-10
abc
2
B
100

2017-11
abc
2
B
100

2017-12
abc
2
B
100

2018-01
abc
2
B
100

2018-02
abc
2
B
100

2018-03
abc
2
B
100

2018-04
abc
2
B
0

2018-05
abc
2
B
0

2018-06
abc
2
B
0

2018-07
abc
2
B
0

2018-08
abc
2
B
0

2018-09
abc
2
B
0

2018-10
abc
2
B
0

2018-11
abc
2
B
0

2018-12
abc
2
B
0

2019-01
abc
2
B
0

2019-02
abc
2
B
0

2019-03
abc
2
B
0

2016-04
xyz
1
A
0

2016-05
xyz
1
A
0

2016-06
xyz
1
A
0

2016-07
xyz
1
A
0

2016-08
xyz
1
A
0

2016-09
xyz
1
A
0

2016-10
xyz
1
A
0

2016-11
xyz
1
A
0

2016-12
xyz
1
A
0

2017-01
xyz
1
A
0

2017-02
xyz
1
A
0

2017-03
xyz
1
A
0

2017-04
xyz
1
A
0

2017-05
xyz
1
A
0

2017-06
xyz
1
A
0

2017-07
xyz
1
A
0

2017-08
xyz
1
A
0

2017-09
xyz
1
A
0

2017-10
xyz
1
A
0

2017-11
xyz
1
A
0

2017-12
xyz
1
A
0

2018-01
xyz
1
A
0

2018-02
xyz
1
A
0

2018-03
xyz
1
A
0

2018-04
xyz
1
A
0

2018-05
xyz
1
A
0

2018-06
xyz
1
A
0

2018-07
xyz
1
A
0

2018-08
xyz
1
A
0

2018-09
xyz
1
A
0

2018-10
xyz
1
A
0

2018-11
xyz
1
A
0

2018-12
xyz
1
A
150

2019-01
xyz
1
A
150

2019-02
xyz
1
A
150

2019-03
xyz
1
A
150

MONTH	SITE	CHANNEL	TYPE	YTD_REVENUE
2017-01-01 00:00:00	abc	1	A	0
2017-02-01 00:00:00	abc	1	A	50
2017-03-01 00:00:00	abc	1	A	50
2017-04-01 00:00:00	abc	1	A	50
2017-05-01 00:00:00	abc	1	A	50
2017-06-01 00:00:00	abc	1	A	50
2017-07-01 00:00:00	abc	1	A	50
2017-08-01 00:00:00	abc	1	A	50
2017-09-01 00:00:00	abc	1	A	50
2017-10-01 00:00:00	abc	1	A	50
2017-11-01 00:00:00	abc	1	A	50
2017-12-01 00:00:00	abc	1	A	50
2017-01-01 00:00:00	abc	2	B	0
2017-02-01 00:00:00	abc	2	B	0
2017-03-01 00:00:00	abc	2	B	0
2017-04-01 00:00:00	abc	2	B	100
2017-05-01 00:00:00	abc	2	B	100
2017-06-01 00:00:00	abc	2	B	100
2017-07-01 00:00:00	abc	2	B	100
2017-08-01 00:00:00	abc	2	B	100
2017-09-01 00:00:00	abc	2	B	100
2017-10-01 00:00:00	abc	2	B	100
2017-11-01 00:00:00	abc	2	B	100
2017-12-01 00:00:00	abc	2	B	100
2018-01-01 00:00:00	xyz	1	A	0
2018-02-01 00:00:00	xyz	1	A	0
2018-03-01 00:00:00	xyz	1	A	0
2018-04-01 00:00:00	xyz	1	A	0
2018-05-01 00:00:00	xyz	1	A	0
2018-06-01 00:00:00	xyz	1	A	0
2018-07-01 00:00:00	xyz	1	A	0
2018-08-01 00:00:00	xyz	1	A	0
2018-09-01 00:00:00	xyz	1	A	0
2018-10-01 00:00:00	xyz	1	A	0
2018-11-01 00:00:00	xyz	1	A	0
2018-12-01 00:00:00	xyz	1	A	150

MONTH	SITE	CHANNEL	TYPE	YTD_REVENUE
2016-04	abc	1	A	0
2016-05	abc	1	A	0
2016-06	abc	1	A	0
2016-07	abc	1	A	0
2016-08	abc	1	A	0
2016-09	abc	1	A	0
2016-10	abc	1	A	0
2016-11	abc	1	A	0
2016-12	abc	1	A	0
2017-01	abc	1	A	0
2017-02	abc	1	A	50
2017-03	abc	1	A	50
2017-04	abc	1	A	0
2017-05	abc	1	A	0
2017-06	abc	1	A	0
2017-07	abc	1	A	0
2017-08	abc	1	A	0
2017-09	abc	1	A	0
2017-10	abc	1	A	0
2017-11	abc	1	A	0
2017-12	abc	1	A	0
2018-01	abc	1	A	0
2018-02	abc	1	A	0
2018-03	abc	1	A	0
2018-04	abc	1	A	0
2018-05	abc	1	A	0
2018-06	abc	1	A	0
2018-07	abc	1	A	0
2018-08	abc	1	A	0
2018-09	abc	1	A	0
2018-10	abc	1	A	0
2018-11	abc	1	A	0
2018-12	abc	1	A	0
2019-01	abc	1	A	0
2019-02	abc	1	A	0
2019-03	abc	1	A	0
2016-04	abc	2	B	0
2016-05	abc	2	B	0
2016-06	abc	2	B	0
2016-07	abc	2	B	0
2016-08	abc	2	B	0
2016-09	abc	2	B	0
2016-10	abc	2	B	0
2016-11	abc	2	B	0
2016-12	abc	2	B	0
2017-01	abc	2	B	0
2017-02	abc	2	B	0
2017-03	abc	2	B	0
2017-04	abc	2	B	100
2017-05	abc	2	B	100
2017-06	abc	2	B	100
2017-07	abc	2	B	100
2017-08	abc	2	B	100
2017-09	abc	2	B	100
2017-10	abc	2	B	100
2017-11	abc	2	B	100
2017-12	abc	2	B	100
2018-01	abc	2	B	100
2018-02	abc	2	B	100
2018-03	abc	2	B	100
2018-04	abc	2	B	0
2018-05	abc	2	B	0
2018-06	abc	2	B	0
2018-07	abc	2	B	0
2018-08	abc	2	B	0
2018-09	abc	2	B	0
2018-10	abc	2	B	0
2018-11	abc	2	B	0
2018-12	abc	2	B	0
2019-01	abc	2	B	0
2019-02	abc	2	B	0
2019-03	abc	2	B	0
2016-04	xyz	1	A	0
2016-05	xyz	1	A	0
2016-06	xyz	1	A	0
2016-07	xyz	1	A	0
2016-08	xyz	1	A	0
2016-09	xyz	1	A	0
2016-10	xyz	1	A	0
2016-11	xyz	1	A	0
2016-12	xyz	1	A	0
2017-01	xyz	1	A	0
2017-02	xyz	1	A	0
2017-03	xyz	1	A	0
2017-04	xyz	1	A	0
2017-05	xyz	1	A	0
2017-06	xyz	1	A	0
2017-07	xyz	1	A	0
2017-08	xyz	1	A	0
2017-09	xyz	1	A	0
2017-10	xyz	1	A	0
2017-11	xyz	1	A	0
2017-12	xyz	1	A	0
2018-01	xyz	1	A	0
2018-02	xyz	1	A	0
2018-03	xyz	1	A	0
2018-04	xyz	1	A	0
2018-05	xyz	1	A	0
2018-06	xyz	1	A	0
2018-07	xyz	1	A	0
2018-08	xyz	1	A	0
2018-09	xyz	1	A	0
2018-10	xyz	1	A	0
2018-11	xyz	1	A	0
2018-12	xyz	1	A	150
2019-01	xyz	1	A	150
2019-02	xyz	1	A	150
2019-03	xyz	1	A	150