单个SELECT语句可检索1列值的所有可能组合Oracle

Question

Say I have a column:

COLUMN
Bread
Butter
Toast
Jam

I need a single efficient select query that will return:

COLUMN
Bread Butter
Bread Toast
Bread Jam
Butter Bread
Butter Toast
Butter Jam
Toast Bread
Toast Butter
Toast Jam
Jam Bread
Jam Butter
Jam Toast

Answer 1

The following query should do what you want, it joins the table on itself and removes the rows matching an item to itself.

SELECT 
      T1.COLUMN || ' ' || T2.COLUMN
FROM
      TABLE T1
JOIN
       TABLE T2 ON T2.COLUMN <> T1.COLUMN

Answer 2

select c1 || ' ' || c2
from 
( select column as c1 from table ),
( select column as c2 from table )
where c1 <> c2 -- this avoids the commented 'jam jam' :)

Answer 3

Isn't that just a cross join with a simple filter?

with [Data] as (
         select *
         from (values
             (N'Bread')
           , (N'Butter')
           , (N'Toast')
           , (N'Jam')
         ) as a ([Value])
     )
select a.[Value] + N' ' + b.[Value] as [Value]
from [Data] as a
cross join [Data] as b
where a.[Value] <> b.[Value];