Dual is a dummy table which oracle has provided to retrieve the values of
Environment Variables.
eg. Select user from dual;
Select sysdate from dual; and many other manipulations like
Select 12 * 12 + 3 from dual;
As the ANSI/SQL syntax requires FROM Clause so that's the reason Oracle has
given you this table to retrieve exactly one row whenever required.
as Select 12 * 12 + 3; would certainly give you error. You can also give : -
Select 12 * 12 + 3 from emp but it would provide 14 rows instead of just one
row having results as :
147
147
147
147
147
147
147
147
147
147
147
147
147
147
14 rows selected
-Original Message-
Sent: Wednesday, July 24, 2002 3:08 PM
To: Multiple recipients of list ORACLE-L
what is dual?
On 23 Jul 2002 at 10:53, Farnsworth, Dave wrote:
> ... The rest of us are just goofs.
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