How to convert single row data into a single column in oracle

问题

I have a table like:

column1  column2  column3  column4
A        B        C        D

wants to convert it as:

Column
A
B
C
D

Without using this union all in oracle:

select column1 as Column from dual
union all
select column2 as Column from dual
union all
select column3 as Column from dual
union all
select column4 as Column from dual

回答1:

You can try to use 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

来源：https://stackoverflow.com/questions/50962636/how-to-convert-single-row-data-into-a-single-column-in-oracle