Question

I have a table with two columns with data like this:

1,2
1,3
1,4
2,1
2,2
3,1

I want to select just unique combinations, so out of those I would end up with:

1,2
1,3
1,4
2,2

because 1,2 is the same combination as 2,1 etc

How would I go about that in a SQL statement?

In reality, my table has a third column and I want to add a where clause based on that third column so that only those rows are considered

Answer 1

SELECT * FROM (
    SELECT
        CASE WHEN Col1 <= Col2 THEN Col1 ELSE Col2 END AS Col1,
        CASE WHEN Col1 <= Col2 THEN Col2 ELSE Col1 END AS Col2
    FROM
        MyTable
) Ordered
GROUP BY
    Col1, Col2

You could do it without the subquery by GROUPing on the CASE expressions, but it’s longer to read.