SQL> 
SQL> -- Currently, 9.2.0.1, there does not seem to be an easy way
SQL> -- to append one collection to another
SQL> 
SQL> select * from test2;

C1         C2                                                                   
-- ----------                                                                   
b           2                                                                   
c           3                                                                   
e           1                                                                   
K           6                                                                   
P           0                                                                   
G           0                                                                   
ap          9                                                                   
u           7                                                                   

8 rows selected.

SQL> select * from test3;

C1         C2                                                                   
-- ----------                                                                   
b           2                                                                   
c           3                                                                   
e           4                                                                   
f           5                                                                   
o           9                                                                   
p           1                                                                   

6 rows selected.

SQL> create or replace view t_vw as select * from test2 union all select * from test3;

View created.

SQL> 
SQL> -- No problem BULK COLLECTing from a view
SQL> set serveroutput on
SQL> declare
  2  type x is table of test2%rowtype;
  3  y x;
  4  begin
  5  select * bulk collect into y from t_vw;
  6  dbms_output.put_line('rows loaded: '||y.count);
  7  end;
  8  /
rows loaded: 14                                                                 

PL/SQL procedure successfully completed.

SQL> 
SQL> -- BULK COLLECT from one collection to another
SQL> -- Note that this is just a test to see if it works.
SQL> -- The easier way is to just 'assign' the whole collection, like
SQL> -- w:=x;
SQL> declare
  2  x num_tab_type;
  3  cursor num_cur is select t1.column_value from table(x) t1;
  4  w num_tab_type;
  5  begin
  6  select c2 bulk collect into x from test2;
  7  open num_cur;
  8  fetch num_cur BULK COLLECT into w;
  9  close num_cur;
 10  dbms_output.put_line('Rows loaded: '||w.count);
 11  end;
 12  /
Rows loaded: 8                                                                  

PL/SQL procedure successfully completed.

SQL> 
SQL> -- Error occurrs as soon as opening of the UNION ALL cursor is attempted.
SQL> declare
  2  x num_tab_type;
  3  y num_tab_type;
  4  cursor num_cur is select * from table(x) union all
  5                    select * from table(y);
  6  w num_tab_type;
  7  begin
  8  select c2 bulk collect into x from test2;
  9  select c2 bulk collect into y from test3;
 10  open num_cur;
 11  fetch num_cur BULK COLLECT into w;
 12  close num_cur;
 13  dbms_output.put_line('Rows loaded: '||w.count);
 14  end;
 15  /
declare
*
ERROR at line 1:
ORA-22905: cannot access rows from a non-nested table item 
ORA-06512: at line 4 
ORA-06512: at line 10 


SQL> 
SQL> -- Error occurrs as soon as opening of the UNION ALL cursor is attempted.
SQL> declare
  2  x num_tab_type;
  3  y num_tab_type;
  4  cursor num_cur is select t1.column_value from table(x) t1 union all
  5                    select t2.column_value from table(y) t2;
  6  w num_tab_type;
  7  begin
  8  select c2 bulk collect into x from test2;
  9  select c2 bulk collect into y from test3;
 10  open num_cur;
 11  fetch num_cur BULK COLLECT into w;
 12  close num_cur;
 13  dbms_output.put_line('Rows loaded: '||w.count);
 14  end;
 15  /
declare
*
ERROR at line 1:
ORA-22905: cannot access rows from a non-nested table item 
ORA-06512: at line 4 
ORA-06512: at line 10 


SQL> 
SQL> declare
  2  x num_tab_type;
  3  y num_tab_type;
  4  cursor num_cur is select t1.column_value c1 from table(x) t1 union all
  5                    select t2.column_value c1 from table(y) t2;
  6  w num_tab_type:=num_tab_type();
  7  i number:=0;
  8  begin
  9  select c2 bulk collect into x from test2;
 10  select c2 bulk collect into y from test3;
 11  for rec in num_cur loop
 12    i:= i+1;
 13    w.extend;
 14  --  w(i):=rec.c1;
 15  end loop;
 16  dbms_output.put_line('Rows loaded: '||w.count);
 17  end;
 18  /
declare
*
ERROR at line 1:
ORA-22905: cannot access rows from a non-nested table item 
ORA-06512: at line 4 
ORA-06512: at line 11 


SQL> 
SQL> drop view t_vw;

View dropped.

SQL> 
SQL> spool off