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, rate2, type, min(month) start_dt, 
    last_day(TO_DATE(replace(MAX(month), 202009, '999912'), 'yyyymm')) AS end_dt
from (
	select t1.month, code1, rate1, rate2, type,
		row_number() over(partition by code1 order by t1.month) rn1,
		row_number() over(partition by code1, rate1, rate2, type 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 start_dt


CODE1
RATE1
RATE2
TYPE
START_DT
END_DT


A
0
null
Acc2
201906
30-JUN-19

A
0
null
Acc1
201906
30-JUN-19

A
0
null
Acc2
201907
31-JUL-19

A
0
null
Acc1
201907
31-JUL-19

A
0
null
Acc1
201908
31-AUG-19

A
0
null
Acc2
201908
31-AUG-19

A
1
null
Acc2
201909
30-SEP-19

A
1
null
Acc1
201909
31-OCT-19

A
1
null
Acc2
201910
31-OCT-19

A
1
null
Acc2
201911
31-DEC-19

A
1
null
Acc1
201911
30-NOV-19

A
1
null
Acc1
201912
31-DEC-19

A
1
10
Acc2
202001
29-FEB-20

A
1
10
Acc1
202001
31-JAN-20

A
1
10
Acc1
202002
29-FEB-20

A
1
10
Acc1
202003
31-MAR-20

A
1
10
Acc2
202003
31-MAR-20

A
1
10
Acc1
202004
30-APR-20

A
1
10
Acc2
202004
30-APR-20

A
1
null
Acc2
202005
31-MAY-20

A
1
null
Acc1
202005
31-MAY-20

A
1
null
Acc2
202006
31-JUL-20

A
1
null
Acc1
202006
30-JUN-20

A
1
null
Acc1
202007
31-JUL-20

A
1
null
Acc2
202008
31-AUG-20

A
1
null
Acc1
202008
31-AUG-20

A
1
null
Acc2
202009
31-DEC-99

A
1
null
Acc1
202009
31-DEC-99

CODE1	RATE1	RATE2	TYPE	START_DT	END_DT
A	0	null	Acc2	201906	30-JUN-19
A	0	null	Acc1	201906	30-JUN-19
A	0	null	Acc2	201907	31-JUL-19
A	0	null	Acc1	201907	31-JUL-19
A	0	null	Acc1	201908	31-AUG-19
A	0	null	Acc2	201908	31-AUG-19
A	1	null	Acc2	201909	30-SEP-19
A	1	null	Acc1	201909	31-OCT-19
A	1	null	Acc2	201910	31-OCT-19
A	1	null	Acc2	201911	31-DEC-19
A	1	null	Acc1	201911	30-NOV-19
A	1	null	Acc1	201912	31-DEC-19
A	1	10	Acc2	202001	29-FEB-20
A	1	10	Acc1	202001	31-JAN-20
A	1	10	Acc1	202002	29-FEB-20
A	1	10	Acc1	202003	31-MAR-20
A	1	10	Acc2	202003	31-MAR-20
A	1	10	Acc1	202004	30-APR-20
A	1	10	Acc2	202004	30-APR-20
A	1	null	Acc2	202005	31-MAY-20
A	1	null	Acc1	202005	31-MAY-20
A	1	null	Acc2	202006	31-JUL-20
A	1	null	Acc1	202006	30-JUN-20
A	1	null	Acc1	202007	31-JUL-20
A	1	null	Acc2	202008	31-AUG-20
A	1	null	Acc1	202008	31-AUG-20
A	1	null	Acc2	202009	31-DEC-99
A	1	null	Acc1	202009	31-DEC-99