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orientdbgraph-databasesnosql

Select distinct vertex in OrientDb

I have a database with the following data:

Vertex

Country              City                 Hotel
--------------       --------------       ---------------------------
ID      Name         ID      Name         ID      Name
--------------       --------------       ---------------------------
#16:0   Italia       #17:0   Roma         #18:0   Residence Barberini
                                          #18:1   Santa Prisca

Edges

In                           PartOf
---------------              -------------
From     To                  From     To
---------------              -------------
#18:0    #16:0               #17:0    #16:0
#18:0    #17:0
#18:1    #17:0

I would like to extract all the hotels in Italy where they can be extracted directly following the edge In or indirectly following the edge PartOf and for each element PartOf another following the edge In.

Basically the result expected is

#18:0   Residence Barberini   (direct from Italia)
#18:1   Santa Prisca          (traversing Roma)

I used the following query 

select distinct(h) from 
(select in('in') as h from (traverse in('partOf') from #16:0))

and I get the following results:

#18:0
#18:0, #18:1

How it is possible to retrieve only the distinct Hotels efficiently? The expected result should be

#18:0
#18:1   (instead of #18:0, #18:1)

Thank you!

Solution

  • You can use 

    select distinct(h) from 
(select in('in') as h from (traverse in('partOf') from #16:0) unwind h)