Table1( PERSON_ID Varchar(50), project Varchar(50) )

------------------------------ Commands Entered ------------------------------
SELECT VARCHAR(person_id, 10) AS person_id
     , INSERT(
          XMLCAST(
             XMLGROUP(
                XMLTEXT(', ' || project) AS a
                ORDER BY project)
          AS VARCHAR(50) )
       , 1, 2, '(')
       || ')' AS "projects"
  FROM Table1
 GROUP BY
       person_id
;
------------------------------------------------------------------------------

PERSON_ID  projects                                            
---------- ----------------------------------------------------
0001       (A1, A2, A3)                                        
0002       (A1, B1)                                            
0003       (A1, A3, B1)                                        
0017       -                                                   

  4 record(s) selected.

with Person_in (person_id, proj) as
(
select varchar('0001', 50), varchar('A1', 50)
from sysibm.sysdummy1 
union all
select '0001', 'A2'
from sysibm.sysdummy1 
union all
select '0001', 'A3'
from sysibm.sysdummy1 
union all
select '0002', 'A1'
from sysibm.sysdummy1 
union all
select '0002', 'B1'
from sysibm.sysdummy1 
union all
select '0003', 'A1'
from sysibm.sysdummy1 
union all
select '0003', 'A3'
from sysibm.sysdummy1 
union all
select '0003', 'B1'
from sysibm.sysdummy1 
union all
select '0017', nullif('', '')
from sysibm.sysdummy1 
union all
select '0021', 'C5'
from sysibm.sysdummy1 
union all
select '0021', 'C7'
from sysibm.sysdummy1 
)
,
Person_dst(person_id, proj) as
( 
select distinct person_id, ifnull(proj, ' ')
from Person_in 
)
,
Person_Seq (person_id, proj, seq, Mseq) as
(
select person_id, proj, seq, Mseq
from Person_dst i1, table
(select count(*) + 1 seq from Person_dst i2
  where i1.person_id || i1.proj > i2.person_id || i2.proj ) ss
, table
(select count(*) Mseq from Person_dst) mm
)
,
Person_Final (person_id, projs, seq, Mseq) as 
(
select person_id, varchar( '(' || proj || ')', 2000), 1, Mseq 
  from Person_Seq where seq = 1
Union All
select f1.person_id, replace(f1.projs, ')', ', ' || p1.proj || ')' ), 
       f1.seq + 1, f1.Mseq 
  from Person_Seq p1, Person_Final f1
where p1.seq       = f1.seq + 1
  and p1.person_id = f1.person_id 
  and f1.seq + 1  <= f1.Mseq
Union All
select p1.person_id, '(' || p1.proj || ')', 
       f1.seq + 1, f1.Mseq 
  from Person_Seq p1, Person_Final f1
where p1.seq        = f1.seq + 1
  and p1.person_id <> f1.person_id 
  and f1.seq + 1   <= f1.Mseq
) 
,
Person_Result (person_id, projects) as
(select  person_id, 
         case when projs = '( )' then '-----' else projs end 
  from Person_Final f2  
   where f2.seq = (select max(f3.seq) from Person_Final f3
                    where f3.person_id = f2.person_id      )
)
select * from Person_Result

SQL1239N   On DB2 database servers Version 9.5
           and earlier, pureXML data store features
           can be used only in a single-partition
           database.