ADD Column ON UPDATE TIMESTAMP

I want to alter a table to include modified and created columns. However, I am having trouble with adding the modified column. I get the following error: > SQL Error: ORA-00907: missing right parenthesis 00907. 00000 - "missing right parenthesis" I was reading this Oracle document (http://docs.oracle.com/cd/E17952_01/refman-5.5-en/timestamp-initialization.html) to get an example on how to properly write the ON UPDATE syntax Here is my SQL. ALTER TABLE FOOBAR ADD ( created TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL, modified TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP ); Why am I getting a missing right parenthesis error?