| From: | "Salman Tahir" <salmantahir1(at)gmail(dot)com> |
|---|---|
| To: | pgsql-sql(at)postgresql(dot)org |
| Subject: | cartesian product |
| Date: | 2007-02-19 16:58:26 |
| Message-ID: | 2049e51a0702190858n6932461dgc294d05b035aad53@mail.gmail.com |
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| Lists: | pgsql-sql |
Hi,
I have a query regarding an SQL statement I'm trying to execute. I
have the following table:
sequence
-------------+
AK
AKCMK
CMKA
I execute the following statement (Cartesian product):
SELECT p1.sequence as sequence1, p2.sequence as sequence2
FROM potential_pairs p1, potential_pairs p2
which gives me:
sequence1 | sequence2
----------------+--------------
AK | AK
AK | AKCMK
AK | CMKA
AKCMK | AK
AKCMK | AKCMK
AKCMK | CMKA
CMKA | AK
CMKA | AKCMK
CMKA | CMKA
(9 rows)
I want to eliminate duplicates and by duplicate I mean a tuple such as
{AK, CMKA} should be regarded as the same as {CMKA, AK}. So I would
like the following result:
sequence1 | sequence2
----------------+--------------
AK | AK
AK | AKCMK
AK | CMKA
AKCMK | AKCMK
AKCMK | CMKA
CMKA | CMKA
Any help would be appreciated.
- Salman
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