listagg(distinct column)over()。

子查询可用于 row_number() 确定要包含在 listagg() ,例如:

select listagg(case when seqnum = 1 then column end) within group (order by column) over (order by ?)
from (select t.*, row_number() over (partition by column order by column) as seqnum
      from t
     ) t