Oracle PL/SQL Tutorial/Introduction/dual

Do simple calculation by using dual

SQL>
SQL> select 123 * 456 from dual;
   123*456
----------
     56088
SQL>
SQL> select sysdate from dual;
SYSDATE
----------
26-10-2009
SQL>

The dual Table

1. dual is a table that contains a single row.
2. The dual table has one VARCHAR2 column named dummy.
3. dual contains a single row with the value X.

The structure of the dual table:

SQL>
SQL> DESCRIBE dual;
 Name         Null?    Type
 DUMMY                 VARCHAR2(1)