MySQL select a field's first X bytes

Is there a way in MySQL to select a fields first X bytes? I have a field of type text. I would like to print the first 500 or so bytes of its contents as a summary of the entire field, then having the user click "read more..." or something of that sort for the whole document. I read up on select in the MySQL manual and didn't see much, does anyone out there know of such a feature? Should I just take the whole field into php and do it that way? thanks, Micah Bushouse