How can I insert records 'into null' in Oracle?
One way you could do something like this on Oracle is to use a temporary table with ON COMMIT DELETE ROWS. The rows will "disappear" at the end of the transaction. If you're using a host environment such as JDBC with autocommit, this will make it look like what you describe. If performance is important, this approach will be much faster than the "discarding trigger" approach.

Syntax:

CREATE GLOBAL TEMPORARY TABLE my_table (
  column1 INTEGER,
  column2 VARCHAR2(100),
  ...
)
ON COMMIT DELETE ROWS;


Documentation: http://docs.oracle.com/cd/B28359_01/server.111/b28310/tables003.htm#ADMIN11633