日期加微秒时间加id后四位生成唯一订单号

  function build_order_no($uid){      //uid后四位      $uid_len = strlen($uid);      if ($uid_len != 4){          if ($uid_len>4){              $after_uid = substr($uid,-4);          }else{              $after_uid = '';              for ($i = 1 ; $i < (5 - $uid_len) ;$i++){                  $after_uid .= 0;              }              $after_uid .= $uid;          }      }else{          $after_uid = $uid;      }      //获得微秒数      $un_number = substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);      return date('ymdhis').$un_number.$after_uid;  }  复制代码