RE: select only 1 pair

select id1,id2 from your_table where id2>=id1
union
select id2,id1 from your_table where id2<id1;

should work

From: Shaozhong SHI <shishaozhong(at)gmail(dot)com>
Sent: Monday, October 24, 2022 4:44 PM
To: pgsql-sql <pgsql-sql(at)lists(dot)postgresql(dot)org>
Subject: select only 1 pair

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 ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍
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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

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