How can I alter multiple tables at once in mysql?

Question

I am trying to alter multiple tables and change the size of the username VARCHAR column to 999 as its current size is too small and now things are screwed up. How can I do this?

I have tried the following and it worked for one table but when trying to update multiple table names it returned errors:

ALTER TABLE  `TABLE_NAME` CHANGE `username` VARCHAR( 999 ) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL