Re: Uses of Dual

Phil Herring wrote:
>
> In article <01bb8f9a$f0fa6d60$80c270ce_at_rasta.access.one.net> Chad Brack, cbrack_at_us.oracle.com writes:
> >Selecting from dual is used for the computing of any constant expression.
> >Since dual only has one row, the result of the expression is returned only
> >one. 'select :variable * 9000 from dual', 'select sysdate + 1 from dual',
> >etc.
>
> It's also common to get SYSDATE this way.
>
> For a cruel practical joke, try adding an extra row to DUAL :-)
>
> ---------------------------------------------------------------------------
> Copyright 1996 Phil Herring. This article may not be reproduced for profit.
> ---------------------------------------------------------------------------

Unfortunately, someone in my company must have seen your "practical joke". It locked up our Oracle Applications every time someone tried to save a record that used a sequencer. Dual had two rows which returned two sequence numbers for each attempt to insert. After much effort we found and resolved the problem.

I recommend that people DON'T play unless they know the consequences to the user community and database. Received on Thu Aug 22 1996 - 00:00:00 CEST