I am using PHP, AS3 and mysql. I have a website. A flash(as3) website. The flash website store the members' information in mysql database through php. In "members" table, i have "id" as the primary key and "username" as a unique field. Now my situation is: When flash want to display a member's profile. My questions: Should Flash pass the member "ID" or "username" to php to process the mysql query? Is there any different passing the "id" or "username"? Which one is more secure? Which one you recommend? I would like to optimize my website in terms of security and performance.