PHP generates a unique digital ID method Rollup _php Tips

Regarding the issue of generating a unique digital ID, is it necessary to generate a random number using Rand and then go to the database query for this number? Feel this kind of words a little time-consuming, is there any other way?

Of course not, in fact there are two ways to solve.

1. If you only use PHP instead of database, the timestamp + random number is the best method, and do not repeat;

2. If you need to use a database, you also need to associate some other data with this ID. Then give the ID of the table in the MySQL database a auto_increment attribute, each time you insert a piece of data, the ID is automatically +1, and then use MYSQL_INSERT_ID () or last_insert_id () to return the self-added ID.

Of course, there is already a workaround for this problem, and using the PHP UUID extension is a perfect solution to this problem, and this extension produces a unique, fully digital signature.

If you do not use composer please refer to Https://github.com/lootils/uuid,

If your project is built based on composer, please refer to the Https://github.com/ramsey/uuid

The specific source code I do not carry, the small partners themselves take down can be used directly

PHP generates a unique identifier code example:

<? 
Generates a unique identifier  
//SHA1 () function, the Secure Hash Algorithm (SHA1) functions  
Create_unique () {  
$data = $_server[' http_user_agent ']. $_ server[' REMOTE_ADDR ']  
. Time () rand ();  
Return SHA1 ($DATA);  
Return MD5 (Time (). $data);  
return $data; 
> 

PHP generates a unique identifier function description and example

<?  
$newhash = Create_unique ();  
echo $newhash;  
? >

To share one more

* * Signal Volume (semaphore).
 * This is a wrapper class that addresses the different implementations of the "semaphore" under different platforms.
 * At present this class is only symbolic, in the Windows platform is actually empty run (and does not really implement mutexes).
  * * Class Semwrapper {private $hasSemSupport;
  Private $sem;

  Const SEM_KEY = 1;
    Public Function __construct () {$this->hassemsupport = function_exists (' Sem_get ');
    if ($this->hassemsupport) {$this->sem = Sem_get (Self::sem_key);
    The public function acquire () {if ($this->hassemsupport) {return Sem_acquire ($this->sem);
  return true;
    The public Function release () {if ($this->hassemsupport) {return sem_release ($this->sem);
  return true;
 }/* * Sequence number generator.

  * * Class Seqgenerator {const SHM_KEY = 1;
   /** * Initialize the sequence number generator.
   * The first call is valid only after the server is started, and calling this method after it has no practical effect.
   * @param int $start produces a sequence number starting value.
   * @return Boolean returns true to indicate success.
    /static Public function init ($start = 1) {//Mutex is achieved by semaphore, avoiding access to shared memory $SW = new Semwrapper;
   if (! $SW->acquire ()) {   return false;
    //Open Shared memory $shm _id = Shmop_open (Self::shm_key, ' n ', 0644, 4);
      if (Empty ($shm _id)) {//due to use ' n ' mode, if the shared memory cannot be opened, it can be assumed that the shared memory has been created without having to initialize $SW->release () again;
    return true;
    ///write initial value in shared memory $size = Shmop_write ($shm _id, pack (' L ', $start), 0);
      if ($size!= 4) {shmop_close ($shm _id);
      $SW->release ();
    return false;
    ///Turn off shared memory, release semaphore Shmop_close ($shm _id);
    $SW->release ();
  return true;
   /** * produces the next sequence number.
    * The sequence number produced by the @return int */static public function next () {//mutual exclusion through semaphores to avoid access to shared memory $SW = new Semwrapper;
    if (! $SW->acquire ()) {return 0;
    //Open Shared memory $shm _id = Shmop_open (Self::shm_key, ' W ', 0, 0);
      if (Empty ($shm _id)) {$SW->release ();
    return 0;
    //Read sequence number from shared memory $data = Shmop_read ($shm _id, 0, 4);
      if (empty ($data)) {$SW->release ();
    return 0; } $arr = Unpack(' L ', $data);

    $seq = $arr [1];
    Writes the next sequence number to the shared memory $size = Shmop_write ($shm _id, pack (' L ', $seq + 1), 0);
      if ($size!= 4) {$SW->release ();
    return 0;
    ///Turn off shared memory, release semaphore Shmop_close ($shm _id);
    $SW->release ();
  return $seq;
}} $a = Seqgenerator::init (time ());

Var_dump ($a);
  For ($i =0 $i < $i + +) {$seq = Seqgenerator::next ();
Var_dump ($SEQ); }

OK, let's get to the bar today, and I want to learn PHP to help you.