Summary of methods for generating unique non-repeating numbers in PHP

How does PHP generate a unique and non-repeating number? Many times, for example, orders require us to generate a unique number. Under normal circumstances, the uniqid() provided by PHP can meet the needs, but in times of high concurrency, we need a better solution to generate unique and non-repeating numbers. This article will share example code, I hope it will be helpful to everyone.

There was an e-commerce project a while ago that required generating an order number. The consideration at the time was simple, take the system time and add a random number, or use the uniqid() method. Carefully consider the above method. When the customer purchases a small amount, the possibility of order duplication is zero. However, duplication of order numbers generated during the peak purchase period is very likely to occur.

First type

return date('Ymd') . str_pad(mt_rand(1, 99999), 5, '0', STR_PAD_LEFT);

Second type

return date('Ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);

Third type

//生成24位唯一订单号码，格式：YYYY-MMDD-HHII-SS-NNNN,NNNN-CC，其中：YYYY=年份，MM=月份，DD=日期，HH=24格式小时，II=分，SS=秒，NNNNNNNN=随机数，CC=检查码
 @date_default_timezone_set("PRC");
 while(true){
  //订购日期
  $order_date = date('Y-m-d');
  //订单号码主体（YYYYMMDDHHIISSNNNNNNNN）
  $order_id_main = date('YmdHis') . rand(10000000,99999999);
  //订单号码主体长度
  $order_id_len = strlen($order_id_main);
  $order_id_sum = 0;
  for($i=0; $i<$order_id_len; $i++){
  $order_id_sum += (int)(substr($order_id_main,$i,1));
  }
  //唯一订单号码（YYYYMMDDHHIISSNNNNNNNNCC）
  $order_id = $order_id_main . str_pad((100 - $order_id_sum % 100) % 100,2,&#39;0&#39;,STR_PAD_LEFT);

Fourth type:

After searching on the Internet, I found that this classmate’s idea is quite good, redtamo. Please go and have a look at the details. I will give a brief overview. This method uses English letters. , year, month, day, Unix timestamp and microseconds, random numbers, the possibility of repetition is greatly reduced, which is still very good. The use of letters is very representative, one letter corresponds to a year, a total of 16 digits, no more, no less, haha.

<?php 
$yCode = array(&#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;);
$orderSn = $yCode[intval(date(&#39;Y&#39;)) - 2011] . strtoupper(dechex(date(&#39;m&#39;))) . date(&#39;d&#39;) . substr(time(), -5) . substr(microtime(), 2, 5) . sprintf(&#39;%02d&#39;, rand(0, 99));
?>

Generation effect:

A422694333616096

Alas, it’s a pity that this method was not used in the final project, saying that it was unnecessary. complex, - -!

The above four methods are all the content shared with you in this article. I hope you will like it.

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