SQL Create a new calculated column based on values of multi rows and cols

I have a data about airline’s booking, using Oracle db, sample is structured as below:

• Recordlocator is booking code
• Sequencenmbr: whenever there is a change in booking, it records new status of a booking with higher Sequencenmbr. So the highest Sequencenmbr in the database shows the latest/current status of bookings
• Sequenceair: is the sequence of flights in bookings, it may be one or many flights in a booking
• DepartAirport: is from airport
• ArrAirport: is to airport.

So the question is, I would like to create new Itinerary column that shows full Itinerary of booking in every rows, which is combination of DepartAirport of each row (in order of SequenceAir) and ArrAirport of a last row. Could anyone help me with the SQL statement or give some links to read?

It has to group by Recordlocator, Sequencenmbr and order by SequenceAir. It should look like this:

Recordlocator	Sequencenmbr	SequenceAir	DepartureDateTime	DepartAirport	ArrAirport	Itinerary
GQWYGM	32	1	25/11/18 16:40	RGN	SIN	RGN-SIN-JKT-SIN-RGN
GQWYGM	32	2	26/11/18 09:35	SIN	JKT	RGN-SIN-JKT-SIN-RGN
GQWYGM	32	3	29/11/18 06:50	JKT	SIN	RGN-SIN-JKT-SIN-RGN
GQWYGM	32	4	29/11/18 11:00	SIN	RGN	RGN-SIN-JKT-SIN-RGN
GQWYGM	33	1	25/11/18 16:40	RGN	SIN	RGN-SIN-MNL-SIN-RGN
GQWYGM	33	2	26/11/18 09:35	SIN	MNL	RGN-SIN-MNL-SIN-RGN
GQWYGM	33	3	29/11/18 06:50	MNL	SIN	RGN-SIN-MNL-SIN-RGN
GQWYGM	33	4	29/11/18 11:00	SIN	RGN	RGN-SIN-MNL-SIN-RGN

Manythanks

Answer

select Recordlocator , Sequencenmbr, Sequenceair , DepartAirport, ArrAirport, departureDateTime
     , LISTAGG(
           (
             case 
                when last_arrAirport = DepartAirport then arrAirport -- removes duplicates when last arrival and current departure are the same
                else DepartAirport||'-'||ArrAirport
             end
           )
       ,'-') 
       WITHIN GROUP(ORDER BY SequenceAir) -- order by
         OVER (PARTITION BY Recordlocator, Sequencenmbr) list -- group by
 from (
      select taskStack.* -- all data from your table
          ,  lag(ArrAirport) over (PARTITION BY Recordlocator, Sequencenmbr -- group by
                                   order by Recordlocator,Sequencenmbr,Sequenceair) last_arrAirport -- arrAirport from previous row
        from taskStack
 ) 
 order BY Recordlocator,Sequencenmbr,Sequenceair