怎么用自关联的方法求2021年的同环比啊

Question

数据如下：
CREATE TABLE T_SALES (ID NUMBER(3),YEAR NUMBER(10),MONTH NUMBER(3),INCOME NUMBER(10,2));
INSERT INTO T_SALES VALUES('1',2020,'1','121.14');
INSERT INTO T_SALES VALUES('2',2020,'2','98.19');
INSERT INTO T_SALES VALUES('3',2020,'3','111.78');
INSERT INTO T_SALES VALUES('4',2020,'4','91.91');
INSERT INTO T_SALES VALUES('5',2020,'5','222.11');
INSERT INTO T_SALES VALUES('6',2020,'6','81.38');
INSERT INTO T_SALES VALUES('7',2020,'7','116.65');
INSERT INTO T_SALES VALUES('8',2020,'8','132.45');
INSERT INTO T_SALES VALUES('9',2020,'9','116.76');
INSERT INTO T_SALES VALUES('10',2020,'10','118.98');
INSERT INTO T_SALES VALUES('11',2020,'11','151.77');
INSERT INTO T_SALES VALUES('12',2020,'12','141.26');
INSERT INTO T_SALES VALUES('13',2021,'1','148.13');
INSERT INTO T_SALES VALUES('14',2021,'2','92.19');
INSERT INTO T_SALES VALUES('15',2021,'3','131.78');
INSERT INTO T_SALES VALUES('16',2021,'4','89.91');
INSERT INTO T_SALES VALUES('17',2021,'5','204.37');
INSERT INTO T_SALES VALUES('18',2021,'6','99.21');
INSERT INTO T_SALES VALUES('19',2021,'7','216.69');
INSERT INTO T_SALES VALUES('20',2021,'8','110.42');
INSERT INTO T_SALES VALUES('21',2021,'9','198.76');
INSERT INTO T_SALES VALUES('22',2021,'10','146.12');
INSERT INTO T_SALES VALUES('23',2021,'11','132.86');
COMMIT;

Answer 1

同比
select b.*,(b.INCOME -a.INCOME )/a.INCOME
from T_SALES a join T_SALES b
on a.month=b.month and a.year=b.year-1

环比
select b.,(b.INCOME -a.INCOME )/a.INCOME
from T_SALES a join T_SALES b
on a.year12+a.month=b.year*12+b.month-1