我想生成所有可能的变化，而不重复。我已经准备了一个数据集和查询，以及预期的结果

with t as (
  select 'A' as col1 from dual
  union all
  select 'B' as col1 from dual
  union all
  select 'C' as col1 from dual
)
select * from t

或

with t as (
      select 'A' as col1, 'B' as col2, 'C' as col3 from dual
    )
    select * from t

我想得到什么？：

A;
A;B
A;B;C
A;C
B;
B;C
C;

行的顺序不相关，元素没有顺序，因此它们不能：A;B和B;A
它可以工作，但返回重复的变体：

select sys_connect_by_path( col1, ';' )
from t
connect by nocycle col1 <> prior col1