Sådan konverteres enkeltrækkedata til en enkelt kolonne i Oracle

Du kan prøve at bruge unpivot

select v
from (
  SELECT 'A' column1,'B' column2,'C' column3,'D' column4  from dual
) t
unpivot
(
  v  for val in (column1,column2,column3,column4)
) u;

sqlfiddle:https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=b2105e1010b332ce5b702eba7bfa7f2d">https://dbfiddle.uk/?fiddle=0bfiddle.uk/?fiddle=0122e3d7bfdbms.7bfdbms.711122e31225.711222e311222ce/? a>