SQL question

From: Michel Cadot <micadot{at}altern{dot}org>
Date: Wed, 19 Oct 2005 18:51:38 +0200
Message-ID: <43567999$0$19246$626a54ce@news.free.fr>

Maybe it's a silly question but i can't find the answer. Why can't Oracle resolve "a.dummy" in the following (meaningless) queries (8.1.7.4 & 9.2.0.6)?

SQL> select ( select dummy

  2           from ( select dummy
  3                  from dual b
  4                  where b.dummy = a.dummy
  5                )
  6         ) dummy

  7 from dual a
  8 /

                where b.dummy = a.dummy
                                *

ERROR at line 4:
ORA-00904: "A"."DUMMY": invalid identifier

SQL> select dummy
  2 from dual a
  3 where exists ( select 1

  4                 from ( select dummy
  5                        from dual b
  6                        where b.dummy = a.dummy
  7                )
  8         )
  9  /
                      where b.dummy = a.dummy
                                      *

ERROR at line 6:
ORA-00904: "A"."DUMMY": invalid identifier

Regards
Michel Cadot Received on Wed Oct 19 2005 - 11:51:38 CDT