I don't now what database you use. I think it might be MySQL and as far as I know you can't change the format in the database.
What you can do is to rearrange the date format before you put the value in and when you take it out from the database.
I think there is some code to do this in the code library here at phpbuilder.com. I think that is where I found the code I am using that I add below.
//From database
/*************************************/
function output_date($string)
{
$stringArray = explode("-", $string);
$date = mktime(0,0,0,$stringArray[1],$stringArray[2],$stringArray[0]);
$convertedDate = date("d-m-Y", $date);
return $convertedDate;
}
//To database
/*************************************/
function input_date($string)
{
$stringArray = explode("-", $string);
$date = mktime(0,0,0,$stringArray[1],$stringArray[0],$stringArray[2]);
$convertedDate = date("Y-m-d", $date);
return $convertedDate;
}