SQL & PL/SQL :: How To Create A View Having All Rows From Tables

I have a table as shown below,

SQL> select * from Main_Table;

AA
--------------------
SUB1
SUB2

Here the SUB1 and SUB2 are "tables" and are similar in their structure. The "Main_Table" will be update dynamically and the no of rows in this table will vary.

Now my question , i need to create a view which will have all the rows from these tables ,in the current case it is something like

create or replace view sample
as
select * from SUB1 union all
select * from SUB2

How can this be achived. I tried as shown below:

spool file_to_exe.sql
select 'select * from ' || AA ||' union all ' from Main_table;
spool off

i will end up in a union all "extra" , if i do like this.

how can achieve this ?..