Question

i have a problem with removing duplicate data in rows with different Columns :

SELECT   p1, p2

  FROM   (SELECT   'A' AS p1, 'B' AS p2 FROM DUAL
          UNION
          SELECT   'B' AS p1, 'A' AS p2 FROM DUAL) a;

and the result will be :

P1 P2 
-- -- 
A , B  
B , A  

and I just need A,B or B,A

Answer 1

SELECT   distinct least(p1, p2), greatest(p1, p2)
  FROM   (SELECT   'A' AS p1, 'B' AS p2 FROM DUAL
          UNION
          SELECT   'B' AS p1, 'A' AS p2 FROM DUAL) a;