How can I find a view column's base table column?
Starting with 12c, we have DBMS_UTILITY.EXPAND_SQL_TEXT.

You basically pass the query text through the first, input parameter, and receive the rewritten query back through the second, output parameter.

But since you are on 11.2, you can not use this yet. You can however collect the optimizer trace. If you already ran your query, and have its sql_id:

begin
  dbms_sqldiag.dump_trace
  (
    p_sql_id=&gt;'1a2b3c4d5e6f',
    p_child_number=&gt;0,
    p_component=&gt;'optimizer',
    p_file_id=&gt;'optimzer_trace'
  );
end;
/


Or if you do not know the sql_id and did not run the query before:

alter session set events 'trace[rdbms.sql_optimizer.*]';
-- run your query here, no need to wait for results, it just need to be hard parsed
alter session set events 'trace[rdbms.sql_optimizer.*] off';


These will generate a trace file that you can read and find the final, rewritten query in it.

To be honest, the output produced by all methods can be difficult to read once you have some complex queries, and the way to get them is not so trivial, so I usually end up reading and "parsing" the DDL statements manually...