Horton

select only 1 pair

Shaozhong SHI <shishaozhong@gmail.com>

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From: Shaozhong SHI <shishaozhong@gmail.com>
To: pgsql-sql <pgsql-sql@lists.postgresql.org>
Date: 2022-10-24T14:44:03Z
Lists: pgsql-sql 
There are pair ids.  Each pair is repeated.

id1   id2
1       2
2        1
3         4
4         3

How to only select 1 unique pair for each?

Regards,

David