Help with selecting between two dates

I am using php with MySQL and trying to figure out how to select data created within the last 3 days.

My date is formatted in the database like 09-20-01

Here is what I have been trying to use, but I'm not too sure on how to subtract 3 days from $date1.

$date1 = date("m-d-y");

$date2 = $date1 - 3;

$query = "select * from My_Table WHERE date BETWEEN $date1 AND $date2

What am I doing wrong?

Hi,

$date1 = date("m-d-y");
$date2 = date("m-d-y",mktime(0,0,0,date("m"),date("d") - 3,date("y")));

-Kevin

Also... understanding that 86400 seconds is one day, you could also just use:
$day_limit = 86400 * 3;
$date2 = date("m-d-y", (time() - $day_limit));

MySQL also has a lot of functions you could use for the same purpose, but you can do it in PHP just as well, I guess.. but if you are interested:

$day_limit = 3;
$query = "SELECT * FROM My_Table WHERE TO_DAYS(NOW()) - TO_DAYS(date) <= $day_limit";

Regards

Thank you very much to the both of you. Both examples worked great.