Oracle 18c

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create table your_table (no, done_date, type) as
select 1, date '2021-07-02', 'SAB1' from dual
union all
select 1, null, 'SAB1' from dual
union all
select 1, date '2021-07-03', 'SAB1' from dual
union all
select 2, date '2021-07-06', 'SAB2' from dual
union all
select 2, date '2021-07-07', 'SAB2' from dual
union all
select 2, null, 'SAB3' from dual
union all
select 2, date '2021-07-09', 'SAB3' from dual;
7 rows affected

select no, done_date, type,
  last_value(done_date)
    over (
      partition by type
      order by done_date nulls last
      rows between unbounded preceding and unbounded following
    ) as last_date
from your_table;


NO
DONE_DATE
TYPE
LAST_DATE


1
02-JUL-21
SAB1
null

1
03-JUL-21
SAB1
null

1
null
SAB1
null

2
06-JUL-21
SAB2
07-JUL-21

2
07-JUL-21
SAB2
07-JUL-21

2
09-JUL-21
SAB3
null

2
null
SAB3
null


select no, done_date, type,
  first_value(done_date)
    over (
      partition by type
      order by done_date desc nulls first
      rows between unbounded preceding and unbounded following
    ) as last_date
from your_table;


NO
DONE_DATE
TYPE
LAST_DATE


1
null
SAB1
null

1
03-JUL-21
SAB1
null

1
02-JUL-21
SAB1
null

2
07-JUL-21
SAB2
07-JUL-21

2
06-JUL-21
SAB2
07-JUL-21

2
null
SAB3
null

2
09-JUL-21
SAB3
null

NO	DONE_DATE	TYPE	LAST_DATE
1	02-JUL-21	SAB1	null
1	03-JUL-21	SAB1	null
1	null	SAB1	null
2	06-JUL-21	SAB2	07-JUL-21
2	07-JUL-21	SAB2	07-JUL-21
2	09-JUL-21	SAB3	null
2	null	SAB3	null