The SQL standard uses the AS keyword for column correlation names but it is not used for table correlation names. Also IBM and SYBASE implement the same syntax as Oracle: no AS keyword for table correlation names.
SELECT name, id FROM owner o WHERE NOT EXISTS (SELECT * FROM upfall u WHERE u.owner_id = o.id)
You can define DB objects AS procedure or function etc.
SQL> select 'bla' as my_col 2 from dual; MY_COL ---------- bla SQL> select 'bla' 2 from dual as my_tab; from dual as my_tab * ERROR at line 2: ORA-00933: SQL command not properly ended