Answers for "date format in php yyyy-mm-dd"

php convert date from dd/mm/yyyy to yyyy-mm-dd

$date = DateTime::createFromFormat('d/m/Y', "24/04/2012");
echo $date->format('Y-m-d');

php validate date format yyyy-mm-dd

$date="2012-09-12";

if (preg_match("/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)) {
    return true;
} else {
    return false;
}