Oracle 18c

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create table ranges (
    name varchar2(1),
    range_start integer,
    range_end integer
);
insert into ranges (name, range_start, range_end)
    select 'a', 0, 7 from dual union all
    select 'b', 2, 4 from dual union all
    select 'c', 1, 3 from dual union all
    select 'd', 4, 6 from dual union all
    select 'e', 3, 5 from dual
5 rows affected

with r as (
      select name, range_start as t
      from ranges
      union all
      select null, range_end as t
      from ranges
     )
select r.*,
       (select r2.name
        from ranges r2
        where r2.range_start <= r.t and
              r2.range_end >= r.t
        order by r2.range_start desc
        fetch first 1 row only
       ) as imputed_name
from (select distinct t
      from r
     ) r
order by t
     


T
IMPUTED_NAME


0
a

1
c

2
b

3
e

4
d

5
d

6
d

7
a


with r as (
      select name, range_start as t
      from ranges
      union all
      select null, range_end as t
      from ranges
     ),
     r2 as (
      select r.*,
             (select r2.name
              from ranges r2
              where r2.range_start <= r.t and
                    r2.range_end >= r.t
              order by r2.range_start desc
              fetch first 1 row only
             ) as imputed_name
      from (select distinct t
            from r
           ) r
     )
select imputed_name, t,
       lead(t) over (order by t)
from (select r2.*,
             lag(imputed_name) over ( order by t) as prev_imputed_name
      from r2
     ) r2
where prev_imputed_name is null or prev_imputed_name <> imputed_name


IMPUTED_NAME
T
LEAD(T)OVER(ORDERBYT)


a
0
1

c
1
2

b
2
3

e
3
4

d
4
7

a
7
null