How to compare all row values of a column against all different values of that column using SQL and return in seperate columns

Question

I have a column that has values like this I want to write an SQL statement to return values in two columns which will look like this.

[input] [1]: https://i.sstatic.net/j5GuT.png

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[Output] [2]: https://i.sstatic.net/JHolu.png

Answer 1

You just need to self JOIN your table with column value unequality condition like this

WITH data AS (
    SELECT * FROM (values ('a'), ('b'), ('c'), ('d')) t("column")
)
SELECT d1."column", d2."column"
FROM data d1
JOIN data d2 ON d1."column" != d2."column"
ORDER BY 1, 2