public function destroy()
{
$inTransaction = DB::getInstance()->inTransaction();
if (!$inTransaction) {
DB::getInstance()->beginTransaction();
}
$st = DB::sql("UPDATE card SET status=0 WHERE card=:card");
// 失效卡
$st->bindValue(":card", $this->card, DB::PARAM_STR);
$flag = $st->execute();
if (!$inTransaction) {
DB::getInstance()->commit();
}
return $flag;
}