How to generate a referral code that is absolutely unique and cannot be easily guessed

Do not check in the database

Reply content:

Do not check in the database

<code class="php">function makeCode($t) {
  $time = $t.mt_rand(10,99); // 要是觉得不够可以加上线程ID等。
  $ce = $time[9];
  $xy = array();
  $xy[0] = array('A','F','D','X','G','H','K','U','P','Y','W','P');
  $xy[1] = array('R','G','H','P','X','D','Y','U','K','F','S','Z');
  // ... 不重复的序列即可
  $xy[9] = array('S','K','T','U','E','Q','V','G','R','X','C','J');
  $rb = '';
  for ($i = 12;$i--;) {
    $rb .= $xy[$ce][$time[$i]];
  }
  return $rb;
}

makecode(time())</code>

For absolutely unique please use UUID
For example, if you are using a linux system

<code>echo file_get_contents('/proc/sys/kernel/random/uuid');
// 输出: 6c509fc7-328b-4d82-9af8-60c44e7b84b4</code>

After you get a unique string like the one above, you can do whatever you want with it, such as cutting off the length you need.
There are many ways to generate UUID in PHP. The above is just a simple use. I also recommend a class library link

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If it is a general recommendation code, it does not need to be complicated unless you have a lot of users. If it is an ordinary company, I think this is enough

<code>echo substr(md5(uniqid(mt_rand(1000, 9999), true)), 20);
// 输出:1c7a6db616de </code>

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<code>echo bin2hex(openssl_random_pseudo_bytes(16));
// 输出: 5a8a80e06ffe44fd0a6931707a26f0cc</code>

Similarly, you can also intercept it freely

http://hashids.org/

Just add a verification code