I'm not at all sure I've read you question correctly, but is this the output you are looking for from your sample input? (The quotes are just a sanity check and easily removed)

C:\test>254403
'V_PAID_USERS'
'V_OVERDUE'
'UNPAID_USERS'
'receipts'
[download]

#! perl -slw
use strict;

$/ = ""; # Set paragraph mode (see Perlvar:$/)
while( <DATA>) {
    m[(\w+)\s+as]i and print "'$1'";
}

__DATA__
  create   view V_PAID_USERS as
  select * from users u, subcription s
  where u.user_id=s.user_id and s.balance =< 0;

  CREATE  OR REPLACE VIEW V_OVERDUE
  AS select *
  from
  users u,
  subscription s
  where u.user_id=s.user_id and s.duedate > 60;

  create TABLE UNPAID_USERS as
  select * from users u, subcription s where u.user_id=s.user_id and s
+.balance > 0;

  create view receipts as select * from unpaid_users;
[download]

Setting $/ to '' enables paragraph mode, and which allows you to read each complete statement as a single string. Using the keyword "AS" as an anchor, seems to select the table or view name in each statement. You can easily change \w+ to be more selective about which ones get captured.

As always, if I got it completely wrong, simply ignore me:)