How update field CURRENT_TIMESTAMP?

i have field

updated` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

and do not specify it in the form

how update this field insensibly?

edited May '15

Try this script´╝Ü CREATE TABLE t1 ( a int, ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP );

insert into t1 values(1,CURRENT_TIMESTAMP);

It's work.

more info below : http://dev.mysql.com/doc/refman/5.6/en/timestamp-initialization.html