CODE EXAMPLE FOR PHP

php validate date format

$date="2012-09-12";

if (preg_match("/^(20[0-9]{2})-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)) {
    return true;
} else {
    return false;
}