php生成唯一id/唯一标识符/唯一订单号

/**
 * php 生成唯一id
 * https://blog.csdn.net/hzqghost/article/details/18914681
 */
function guid($factor='',$prefix='',$suffix=''){
    list($usec, $sec) = explode(" ", microtime());  
    $guid = $prefix. $factor. $_SERVER['HTTP_USER_AGENT'] . $_SERVER['REMOTE_ADDR']  
           . $sec . $usec   
           . mt_rand(0,1000000).time(). mt_rand(0,1000000).$suffix;  
    $guid = substr(sha1($guid),8,32); 
    $guid = base_convert($guid,16,36);  
    return $prefix.$guid.$suffix;
}


//生成唯一标识符   //sha1()函数， "安全散列算法（SHA1）"   
function create_unique(){
    $data = $_SERVER['HTTP_USER_AGENT'].$_SERVER['REMOTE_ADDR'].time().rand();
    return sha1($data);//return md5(time().$data);   //return $data;   
}


//生成24位唯一订单号
function create_orderid(){
    return date('Ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}