‘ARB‘.date(‘ymd‘).str_pad($last[0][‘orderby‘] + 1,4,"0",STR_PAD_LEFT),
例子：
$num=128; $num=str_pad($num,4,"0",STR_PAD_LEFT); echo $num;
输出
0128
订单编号自增补零
原文：https://www.cnblogs.com/ZxyPhppython/p/9224447.html
