The dual Table : dual « Introduction « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Introduction
3. dual

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)

SQL> SELECT * FROM dual;

D
-
X

SQL>