as

(

select 'Truck A' , 'A' , 'B' , to_date('02/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck A' , 'B' , 'C' , to_date('02/01/2021 02:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck A' , 'C' , 'D' , to_date('04/01/2021 03:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck B' , 'C' , 'A' , to_date('05/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck B' , 'A' , 'B' , to_date('06/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck C' , 'C' , 'B' , to_date('07/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck C' , 'B' , 'C' , to_date('08/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck C' , 'C' , 'B' , to_date('09/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual union all

select 'Truck C' , 'B' , 'A' , to_date('10/01/2021 01:00:00','dd/mm/yyyy hh24:mi:ss') from dual

)

select vehicle , start_letter, end_letter, date_letter from

(

select vehicle , min_start_lett as start_letter, max_start_lett as end_letter, date_letter,

row_number() over(partition by vehicle order by date_letter desc) as ranking

from

(

select x.* ,

rank() over(partition by vehicle order by start_letter desc, end_letter desc, date_letter desc ) as rn ,

min(start_letter) over(partition by vehicle) as min_start_lett ,

max(end_letter) over(partition by vehicle) as max_start_lett

from x

) d

where rn = ( select max(rn) from x c where c.vehicle = d.vehicle group by vehicle )

) where ranking = 1

;