SELECT   a.unid, wm_concat (b.nr || '/' || b.NAME) NAME
    FROM a, b
   WHERE b.a_unid = a.unid
GROUP BY a.unid

------解决方案--------------------

SQL code

 select  t.id,wmsys.wm_concat(t.v )
  from  (select a.id,b.nr||'/'||b.name v from p1 a ,p2 b where a.id = b.id) t
  group by t.id;