SQL & PL/SQL

I am on Oracle Database 11g Express Edition Release 11.2.0.2.0 - Production

======

I need:

create table my_table_name  
(
  a varchar2(255)
  ,b varchar2(255)
  ,c varchar2(255)
  ,jan int
  ,feb int
  ,mar int
  ,apr int
);
insert into (a, b, c, jan, feb, mar, apr) values ('a', 'b', 'c', 11, 1, 12, 111);

to look like:

Could someone please help me achieve this?

I know of UNION, but I don't want to use it in hopes there's something already there for me, built-in.

with main as
(
  select 
    'jan' date_id
    ,a
    ,b
    ,c
    ,jan as val
  from 
    my_table_name
union all
  select 
    'feb' date_id
    ,a
    ,b
    ,c
    ,feb as val
  from 
    my_table_name
union all
  select 
    'mar' date_id
    ,a
    ,b
    ,c
    ,mar as val
  from 
    my_table_name
union all
  select 
    'apr' date_id
    ,a
    ,b
    ,c
    ,apr as val
  from 
    my_table_name
)
select * from main;

Thanks,

Dorian