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help / color / mirror / Atom feedFrom: William Alves Da Silva <william_silva@unochapeco.edu.br>
To: pgsql-sql <pgsql-sql@lists.postgresql.org>
To: Shaozhong SHI <shishaozhong@gmail.com>
Subject: Re: select only 1 pair
Date: Mon, 24 Oct 2022 12:01:30 -0300
Message-ID: <7f09c27c-c4df-4836-bd29-706ebc5eb154@Spark> (raw)
In-Reply-To: <CA+i5Jwa5VR7vJ=9S-9-d_3HgxQ_MmqwLW9+vqeN=jNDUVSVCHQ@mail.gmail.com>
References: <CA+i5Jwa5VR7vJ=9S-9-d_3HgxQ_MmqwLW9+vqeN=jNDUVSVCHQ@mail.gmail.com>
Hello David,
Try this.
This is an exemple of your table.
SELECT *
FROM (VALUES (1, 2), (2, 1), (3, 4), (4, 1)) t (id1, id2)
id1 |id2 |
------+------+
1| 2|
2| 1|
3| 4|
4| 1|
I think that is what you need
SELECT DISTINCT LEAST(id1, id2) AS id1, GREATEST(id1, id2) AS id2
FROM (VALUES (1, 2), (2, 1), (3, 4), (4, 3)) t (id1, id2)
id1 |id2 |
------+------+
1| 2|
3| 4|
Regards,
William Alves
On 24 Oct 2022 11:44 -0300, Shaozhong SHI <shishaozhong@gmail.com>, wrote:
> 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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To: pgsql-sql@postgresql.org
Cc: william_silva@unochapeco.edu.br, pgsql-sql@lists.postgresql.org, shishaozhong@gmail.com
Subject: Re: select only 1 pair
In-Reply-To: <7f09c27c-c4df-4836-bd29-706ebc5eb154@Spark>
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