How to achieve non-duplicate unique values ​​in php

php method to achieve non-duplicate unique values: 1. You can use the "uniqid()" function to generate a non-duplicate unique identifier; 2. You can use the "session_create_id()" function to generate a unique identifier; 3. Unique identifiers can be generated using the "session_create_id()" function.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, Dell G3 computer.

How to achieve non-duplicate unique values ​​in php?

PHP Generates a unique unique identifier session_create_id()

PHP uniqid() function can be used to generate a unique unique identifier that is based on the microsecond level current timestamp. In cases of high concurrency or extremely short intervals (such as loop code), a large amount of duplicate data will appear. This is repeated even if the second parameter is used.

Use the session_create_id() function to generate a unique identifier. After actual testing, it was found that even if session_create_id() is called cyclically 100 million times, there is no duplication.

php session_create_id() is a new function in PHP 7.1. It is used to generate session id. It cannot be used in lower versions.

PHP uniqid() function can be used to generate a unique identifier that is not repeated, which is based on the current timestamp in microseconds. In cases of high concurrency or extremely short intervals (such as loop code), a large amount of duplicate data will appear. This is repeated even if the second parameter is used.

Use the session_create_id() function to generate a unique identifier. After actual testing, it was found that even if session_create_id() is called cyclically 100 million times, there is no duplication.

php session_create_id() is a new function in PHP 7.1. It is used to generate session id. It cannot be used in lower versions.

<?php
/**
 * PHP生成唯一RequestID类
 * Version: 1.0
 */
class RequestID{ // class start
 
    /**
    * 生成唯一请求id
    * session_create_id 需要php7.1以上版本
    * @return String
    */
    public static function generateV7(){
        // 使用session_create_id()方法创建前缀
        $prefix = session_create_id(date(&#39;YmdHis&#39;));
        // 使用uniqid()方法创建唯一id
        $request_id = strtoupper(md5(uniqid($prefix, true)));
        // 格式化请求id
        return self::format($request_id);
    }
 
    public static function generate(){
        // 创建前缀
        $prefix = self::create_guid(date(&#39;YmdHis&#39;));
        // 使用uniqid()方法创建唯一id
        $request_id = strtoupper(md5(uniqid($prefix, true)));
        // 格式化请求id
        return self::format($request_id);
    }
 
    public static function create_guid($namespace = &#39;&#39;) {  
        static $guid = &#39;&#39;;
        $uid = uniqid("", true);
        $data = $namespace;
        $data .= $_SERVER[&#39;REQUEST_TIME&#39;];
        $data .= $_SERVER[&#39;HTTP_USER_AGENT&#39;];
        $data .= isset($_SERVER[&#39;LOCAL_ADDR&#39;])?$_SERVER[&#39;LOCAL_ADDR&#39;]:$_SERVER[&#39;SERVER_ADDR&#39;];
        $data .= isset($_SERVER[&#39;LOCAL_PORT&#39;])?$_SERVER[&#39;LOCAL_PORT&#39;]:$_SERVER[&#39;SERVER_PORT&#39;];
        $data .= $_SERVER[&#39;REMOTE_ADDR&#39;];
        $data .= $_SERVER[&#39;REMOTE_PORT&#39;];
        $hash = strtoupper(hash(&#39;ripemd128&#39;, $uid . $guid . md5($data)));
        $guid = &#39;{&#39; . 
          substr($hash, 0, 8) .
          &#39;-&#39; .
          substr($hash, 8, 4) .
          &#39;-&#39; .
          substr($hash, 12, 4) .
          &#39;-&#39; .
          substr($hash, 16, 4) .
          &#39;-&#39; .
          substr($hash, 20, 12) .
          &#39;}&#39;;
        return $guid;
    }
 
    /**
    * 格式化请求id
    * @param String $request_id 请求id
    * @param Array $format  格式
    * @return String
    */
    private static function format($request_id, $format=&#39;8,4,4,4,12&#39;){
        $tmp = array();
        $offset = 0;
        $cut = explode(&#39;,&#39;, $format);
        // 根据设定格式化
        if($cut){
            foreach($cut as $v){
                $tmp[] = substr($request_id, $offset, $v);
                $offset += $v;
            }
        }
        // 加入剩余部分
        if($offset<strlen($request_id)){
            $tmp[] = substr($request_id, $offset);
        }
        return implode(&#39;-&#39;, $tmp);
    }
} // class end
 
// 生成10个请求id
for($i=0; $i<10; $i++){
 echo RequestID::generate().PHP_EOL.&#39;<br>&#39;;
}

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