Yup. That latter date looks an awful lot like a Unix timestamp ... assuming it is, there are two ways to accomplish the conversion: 1) Do it yourself with something like mktime(), or 2) let MySQL do it for you with UNIX_TIMESTAMP() .
Method #1:
$dString = '07/09/2003'; //day, month, year
$dArray = explode('/', $dString);
$date = mktime(0, 0, 0, $dArray[1], $dArray[0], $dArray[2]);
//make Unix timestamp for 00:00 07 Sept 2003
$query = "INSERT INTO dbName SET date=$date";
Method #2:
$dateString = '07/09/2003';
$ds = explode('/', $dateString);//create an array - in order day, month, year
$query = "INSERT INTO dbName SET date=UNIX_TIMESTAMP($ds[2]$ds[1]$ds[0])";
I'd prefer the second way, but either is alright ... just don't forget to make sure the day/month/year order is correct for whatever function you're using.