Oracle 11g Release 2

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CREATE TABLE SALES (PROD_ID NUMBER(6), TIME_ID DATE, AMOUNT_SOLD NUMBER(10,2));
CREATE TABLE TIMES (TIME_ID DATE, CALENDAR_YEAR NUMBER, CALENDAR_MONTH_DESC NUMERIC);
INSERT INTO SALES VALUES (1, DATE '2018-01-01', 100);
1 rows affected

INSERT INTO SALES VALUES (1, DATE '2018-02-01', 200);
1 rows affected

INSERT INTO SALES VALUES (1, DATE '2018-03-01', 150);
1 rows affected

INSERT INTO TIMES VALUES(DATE '2018-01-01', 2018, 1);
1 rows affected

INSERT INTO TIMES VALUES (DATE '2018-02-01', 2018, 2);
1 rows affected

INSERT INTO TIMES VALUES (DATE '2018-03-01', 2018, 3);
1 rows affected

/* aggregated sales by year-month */
SELECT
    T.CALENDAR_YEAR AS Year,
    T.CALENDAR_MONTH_DESC AS Month,
    SUM(S.AMOUNT_SOLD) AS AmountOfMoney
FROM
    SALES S
JOIN
    TIMES T
    ON T.TIME_ID = S.TIME_ID
WHERE S.PROD_ID = 1
GROUP BY ROLLUP (T.CALENDAR_YEAR, T.CALENDAR_MONTH_DESC)
ORDER BY GROUPING (T.CALENDAR_YEAR) DESC, 
         GROUPING (T.CALENDAR_MONTH_DESC) DESC, 
         CALENDAR_YEAR ASC,
         CALENDAR_MONTH_DESC ASC;


YEAR
MONTH
AMOUNTOFMONEY


null
null
450

2018
null
450

2018
1
100

2018
2
200

2018
3
150