1

How would I do this in postgres :

Lets say I have an x and a y and I want to show all possible combinations :

xx
yy
xy
yx

How can I make postgres do this for me ?

1 Answer 1

7
with characters (c) as (
  select unnest(string_to_array('xy', null))
) 
select *
from characters c1
  cross join characters c2

Edit:

Apparently this does not work in 8.4, but the following should:

with characters (c) as (
  select unnest(regexp_split_to_array('xy', ''))
) 
select *
from characters c1
  cross join characters c2

Thanks to Bruno for testing this.

6
  • that gives me no output I'm affraid :/ Commented Dec 11, 2011 at 16:30
  • No output? Works fine over here, PostgreSQL version 9.1 used to test. Commented Dec 11, 2011 at 16:32
  • I'm still running 8.4 :( Commented Dec 11, 2011 at 16:37
  • 1
    @LucasKauffman: That should work on 8.4 as well (it has CTEs, unnest and string_to_array)
    – user1822
    Commented Dec 11, 2011 at 16:53
  • 2
    I couldn't get it to work with 8.4 either, but replacing string_to_array('xy', null) with regexp_split_to_array('xy', '') works. Credit to this thread, which may have something to do with support for NULL as a delimiter in more recent versions.
    – Bruno
    Commented Dec 11, 2011 at 20:06

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