Question

In SQL server I can print out the value of something with a select statement.

SELECT 'xyz'

SELECT GetDate()

Can I do something similar in Oracle without adding FROM <tablename>?

Answer 1

This is the purpose of the dual table. Oracle supplies the Dual in every database and it’s accessible, by default, to everyone that connects. It’s a single-row, single column table that is useful for testing expressions and pseuducolumns against. Example

SELECT 'xyz' from dual;


SQL> select user,sysdate,lower(user) loweruser, 10*1023 from dual;

USER       SYSDATE    LOWERUSER     10*1023
---------- ---------- ---------- ----------
NKODNER    22-NOV-11  nkodner         10230