DUAL Table

The DUAL table is a special one-row, one-column table present by default in all Oracle RDBMS installations.

The table has a single VARCHAR2(1) column called DUMMY that has a value of ‘X’.

Example 1:

SELECT * FROM DUAL;

returns:

DUMMY
--------
X

Example 2:

SELECT SYSDATE FROM dual;

returns:

15-JUN-2015 17:16:00