Oracle 18c

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CREATE TABLE table1(
   CODE1 VARCHAR(1) NOT NULL 
  ,RATE1  INTEGER  NOT NULL
  , type VARCHAR(10) NOT NULL 
  ,MONTH INTEGER  NOT NULL
  
);


CREATE TABLE table2(
   CODE2 VARCHAR(1) NOT NULL 
  ,RATE2  INTEGER  NOT NULL
  ,MONTH INTEGER  NOT NULL
);
begin
INSERT INTO table1 VALUES ('A',0,'Acc1',201906);
INSERT INTO table1 VALUES ('A',0,'Acc1',201907);
INSERT INTO table1 VALUES ('A',0,'Acc1',201908);
INSERT INTO table1 VALUES ('A',1,'Acc1',201909);
INSERT INTO table1 VALUES ('A',1,'Acc1',201910);
INSERT INTO table1 VALUES ('A',1,'Acc1',201911);
INSERT INTO table1 VALUES ('A',1,'Acc1',201912);
INSERT INTO table1 VALUES ('A',1,'Acc1',202001);
INSERT INTO table1 VALUES ('A',1,'Acc1',202002);
INSERT INTO table1 VALUES ('A',1,'Acc1',202003);
INSERT INTO table1 VALUES ('A',1,'Acc1',202004);
INSERT INTO table1 VALUES ('A',1,'Acc1',202005);
INSERT INTO table1 VALUES ('A',1,'Acc1',202006);
INSERT INTO table1 VALUES ('A',1,'Acc1',202007);
INSERT INTO table1 VALUES ('A',1,'Acc1',202008);
INSERT INTO table1 VALUES ('A',1,'Acc1',202009);
INSERT INTO table1 VALUES ('A',0,'Acc2',201906);
INSERT INTO table1 VALUES ('A',0,'Acc2',201907);
INSERT INTO table1 VALUES ('A',0,'Acc2',201908);
INSERT INTO table1 VALUES ('A',1,'Acc2',201909);
INSERT INTO table1 VALUES ('A',1,'Acc2',201910);
INSERT INTO table1 VALUES ('A',1,'Acc2',201911);
INSERT INTO table1 VALUES ('A',1,'Acc2',201912);
INSERT INTO table1 VALUES ('A',1,'Acc2',202001);
INSERT INTO table1 VALUES ('A',1,'Acc2',202002);
INSERT INTO table1 VALUES ('A',1,'Acc2',202003);
INSERT INTO table1 VALUES ('A',1,'Acc2',202004);
INSERT INTO table1 VALUES ('A',1,'Acc2',202005);
INSERT INTO table1 VALUES ('A',1,'Acc2',202006);
INSERT INTO table1 VALUES ('A',1,'Acc2',202007);
INSERT INTO table1 VALUES ('A',1,'Acc2',202008);
INSERT INTO table1 VALUES ('A',1,'Acc2',202009);
end;
/
1 rows affected

begin
INSERT INTO table2 VALUES ('A',10,202001);
INSERT INTO table2 VALUES ('A',10,202002);
INSERT INTO table2 VALUES ('A',10,202003);
INSERT INTO table2 VALUES ('A',10,202004);
end;
/
1 rows affected

select code1, rate1, coalesce(rate2, 0), type, min(month) start_dt, max(month) end_dt
from (
	select t1.month, t1.code1, t1.rate1, t2.rate2, type,
		row_number() over(partition by t1.code1, t1.type order by t1.month) rn1,
		row_number() over(partition by t1.code1, t1.type, t1.rate1, t2.rate2 order by t1.month) rn2
	from table1 t1 
	left join table2 t2 on t1.code1 = t2.code2 and t1.month = t2.month
) t
group by code1, rate1, rate2, type, rn1 - rn2
order by type, start_dt


CODE1
RATE1
COALESCE(RATE2,0)
TYPE
START_DT
END_DT


A
0
0
Acc1
201906
201908

A
1
0
Acc1
201909
201912

A
1
10
Acc1
202001
202004

A
1
0
Acc1
202005
202009

A
0
0
Acc2
201906
201908

A
1
0
Acc2
201909
201912

A
1
10
Acc2
202001
202004

A
1
0
Acc2
202005
202009
CODE1	RATE1	COALESCE(RATE2,0)	TYPE	START_DT	END_DT
A	0	0	Acc1	201906	201908
A	1	0	Acc1	201909	201912
A	1	10	Acc1	202001	202004
A	1	0	Acc1	202005	202009
A	0	0	Acc2	201906	201908
A	1	0	Acc2	201909	201912
A	1	10	Acc2	202001	202004
A	1	0	Acc2	202005	202009