Връща всички възможни комбинации от стойности на колони в SQL

Ако приемем поне SQL 2005 за CTE:

;with cteAllColumns as (
    select col1 as col
        from YourTable
    union
    select col2 as col
        from YourTable
)
select c1.col, c2.col 
    from cteAllColumns c1 
        cross join cteAllColumns c2 
    where c1.col < c2.col
    order by c1.col, c2.col