Oracle SQL insert into with With clause

Question

I'm new to sql, so maybe it is a dumb question, but is there any possibility to use With clause with Insert Into? Or are there any common workarounds? I mean something like this:

With helper_table As (
Select * From dummy2
)
Insert Into dummy1 Values (Select t.a From helper_table t Where t.a = 'X' );

Thx!

My example is too dummy, so I add some extended code (thx for the answers so far).

INSERT
INTO    dummy values (a,b)  //more values
WITH    helper_table AS
    (
    SELECT  *
    FROM    dummy2
    )
WITH    helper_table2 AS   //from more tables
    (
    SELECT  *
    FROM    dummy3
    )         
SELECT  t.value as a, t2.value as b
FROM    helper_table t 
join helper_table t2 on t.value = t2.value //some join
WHERE   t.value = 'X' and t2.value = 'X'   //other stuff

Answer 1

You may use as many 'helper_tables' as you wish.

create table t(helper1 varchar2(50) , helper2 varchar2(50) , dataElement varchar2(50) );


insert into t(helper1, helper2, dataelement)
with
     de as(select level lvl from dual connect by level <10)
     ,h1 as (select lvl, lvl/1.5 hp from de)
     ,h2 as (select lvl,  lvl/2 hp2 from de)
select h1.hp , h2.hp2, de.lvl
  from de 
        inner join
       h1 on de.lvl = h1.lvl
        inner join
       h2 on de.lvl = h2.lvl
/

With this in mind, you may be able to do all of your joins via normal joining of the tables to the master table

Answer 2

INSERT
INTO    dummy1
WITH    helper_table AS
        (
        SELECT  *
        FROM    dummy2
        )
SELECT  t.a
FROM    helper_table t
WHERE   t.a = 'X'

Answer 3

You can do something like

INSERT INTO dummy1
  WITH helper_table AS (
    SELECT *
      FROM dummy2
    )
  SELECT t.a
    FROM helper_table t
   WHERE t.a = 'X';

For your updated query

INSERT
INTO    dummy values (a,b)  //more values
WITH    helper_table AS
    (
    SELECT  *
    FROM    dummy2
    ),
        helper_table2 AS   //from more tables
    (
    SELECT  *
    FROM    dummy3
    )         
SELECT  t.value as a, t2.value as b
FROM    helper_table t 
join helper_table t2 on t.value = t2.value //some join
WHERE   t.value = 'X' and t2.value = 'X'   //other stuff

Answer 4

Keep in mind, using CTE's is intended for a small amount of data. Having thousands of rows in CTE's may cause performance degradation.

This is because all the helper table content is stored in PGA if not in the TEMP