There are a whole bunch of date-formatting utilities available in MySQL:
Assuming your datefield was named 'last_modified', you could format it's return value from the database using the DATE_FORMAT() function like this:
SELECT DATE_FORMAT(last_modified,"%m/%d/%Y") FROM table
Or, if you prefer to format the query result using PHP, you can select the temporal data as a UNIX timestamp and use PHP to manipulate the returned integer value:
SELECT FROM_UNIXTIME(last_modified) FROM table
then format the value using the date() function:
date("m/d/y",$last_modified)
Have fun...