Dynamic Oracle Pivot_In_Clause

I'm kinda stuck. I want to do a user-role-relationship pivot table and my query so far looks like this:

WITH PIVOT_DATA AS (
     SELECT *
     FROM
     (
         SELECT USERNAME, GRANTED_ROLE
         FROM DBA_USERS@DB_LINK U LEFT OUTER JOIN DBA_ROLE_PRIVS@DB_LINK R
         ON U.USERNAME = R.GRANTEE
      )
)
SELECT *
FROM PIVOT_DATA
PIVOT
(
    COUNT(GRANTED_ROLE)
    FOR GRANTED_ROLE
    IN('CONNECT') -- Just an example
)
ORDER BY USERNAME ASC;

It works really fine and does the job, but I don't want to write to write any role I want to search for in the pivot_in_clause, because we got like tons of them and I don't want to check every time if there are any changes.

So is there a way to write a SELECT in the pivot_in_clause? I tried it myself:

[...]
PIVOT
(
    COUNT(GRANTED_ROLE)
    FOR GRANTED_ROLE
    IN( SELECT ROLE FROM DBA_ROLES@DB_LINK )
)
[...]

But it always gives me an ORA-00936: "missing expression" in line 1 of the whole query and I don't know why. Can't there be a SELECT in the pivot_in_clause or am I doing it wrong?

You can build dynamic query in your script, look at this example:

variable rr refcursor

declare 
  bb varchar2(4000);
  cc varchar2( 30000 );
begin 
    WITH PIVOT_DATA AS (
         SELECT *
         FROM
         (
             SELECT USERNAME, GRANTED_ROLE
             FROM DBA_USERS U LEFT OUTER JOIN DBA_ROLE_PRIVS R
             ON U.USERNAME = R.GRANTEE
          )
    )
    select ''''|| listagg( granted_role, ''',''' ) 
            within group( order by granted_role ) || '''' as x 
    into bb
    from (
      select distinct granted_role from pivot_data
    )
    ;

    cc := q'[
    WITH PIVOT_DATA AS (
         SELECT *
         FROM
         (
             SELECT USERNAME, GRANTED_ROLE
             FROM DBA_USERS U LEFT OUTER JOIN DBA_ROLE_PRIVS R
             ON U.USERNAME = R.GRANTEE
          )
    )
    SELECT *
    FROM PIVOT_DATA
    PIVOT
    (
        COUNT(GRANTED_ROLE)
        FOR GRANTED_ROLE
        IN(]'  || bb || q'[) -- Just an example
    )
    ORDER BY USERNAME ASC]';

    open :rr for cc;
end;
/

SET PAGESIZE 200
SET LINESIZE 16000
print :rr

Here is the result (only small fragment, because it is very wide and long)

-----------------------------------------------------------------------------------------------------------------------------------
    USERNAME                       'ADM_PARALLEL_EXECUTE_TASK' 'APEX_ADMINISTRATOR_ROLE' 'AQ_ADMINISTRATOR_ROLE' 'AQ_USER_ROLE'        
    ------------------------------ --------------------------- ------------------------- ----------------------- ----------------------
    ANONYMOUS                      0                           0                         0                       0          
    APEX_030200                    0                           0                         0                       0        
    APEX_PUBLIC_USER               0                           0                         0                       0    
    APPQOSSYS                      0                           0                         0                       0   
..............
    IX                             0                           0                         1                       1  
    OWBSYS                         0                           0                         1                       1