Create Unique Image Names

Question

What\'s a good way to create a unique name for an image that my user is uploading?

I don\'t want to have any duplicates so something like MD5($filename) isn\'t suita

Answer 1

as it was mentioned, i think that best way to create unique file name is to simply add time(). that would be like

$image_name = time()."_".$image_name;