Oracle PL/SQL Tutorial/Introduction/dual

Do simple calculation by using dual

   <source lang="sql">

SQL> SQL> select 123 * 456 from dual;

  123*456

---

    56088

SQL> SQL> select sysdate from dual; SYSDATE

---

26-10-2009 SQL></source>

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:

   <source lang="sql">

SQL> SQL> DESCRIBE dual;

Name         Null?    Type
DUMMY                 VARCHAR2(1)</source>