Oracle: I need a "partial" outer join. Look at the image

Question

I hope it's clear. How can I achieve the result showed in the following image?

Answer 1

Just do an outer join but also use coalesce

SELECT
   COALESCE(a.master,b.master) master,
   a.ColA,
   b.ColB
FROM
  a FULL OUTER JOIN B
  ON a.master = b.master
     AND (a.ColA = b.ColB 
          or a.ColA is Null
          or b.ColB is Null)
ORDER BY 
    COALESCE(a.master,b.master),
    COALESCE(a.cola,b.colB)

See it working here

Answer 2

SELECT 
  masters.master AS master,
  TableA.ColA AS ColA,
  TableB.ColB AS ColB,
FROM
    (
      SELECT master FROM TableA
      UNION
      SELECT master FROM TableB
    ) AS masters
    LEFT JOIN TableA ON masters.master=TableA.master
    LEFT JOIN TableB ON masters.master=TableB.master
ORDER BY
    master, ColA, ColB