SQL Query: How to get items from one col paired with another but not vice versa

Question

I need a query that returns all the rows from colA paired with colB but to treat the same values in the opposite direction as duplicates and to be removed.

The best

Answer 1

If you prefer a "clean" SQL solution (without least() or greatest()) this also does your job:

select colA, colB from your_table
where colA > colB 
  or (colB, colA) not in (select colA, colB from your_table)

SQL fiddle