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|
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