具有固定字母位置的php字母数字ID

Question

我需要在 PHP 中创建唯一的字母数字 ID，长度为 6 个字符。

虽然我找到了很多解决这个问题的答案，但我希望将字母定位在 ID 中的特定位置，例如 A1B2C3（第一个、第三个和第五个字符）。

对此我唯一的解决方案是创建 6 个“for”循环（a-z 和 0-9 * 3 次）并将输出插入到数组中，然后插入到 MySQL 表中。肯定不会重复，但是有没有更好的办法？

到目前为止我的代码是：

<?php

   $id=array();

   for($a='A';$a!='AA';$a++){
        for($b=1;$b<=9;$b++){
           for($c='A';$c!='AA';$c++){
              for($d=1;$d<=9;$d++){
                  for($e='A';$e!='AA';$e++){
                     for($f=1;$f<=9;$f++){

                       $id[]=$a.$b.$c.$d.$e.$f;
                     }
                  } 
              }
           }
        }
    }

    foreach ($id as $value) {
        echo "$value \n";
    }
?> 

Answer 1

如果您需要顺序 ID：

// to start
//$numIds = 20000;
//$id = '';

// to add more
$numIds = 1000;
$id = 'A1J5M2'; // put MAX id from DB here

if ( '' !== $id ) { // increment id
  list($aa, $bb, $cc, $dd, $ee, $ff) = str_split($id);
  $arr = [$aa, $bb, $cc, $dd, $ee, $ff];
  list($aa, $bb, $cc, $dd, $ee, $ff) = incc($arr, count($arr) - 1);
}
else {
  list($aa, $bb, $cc, $dd, $ee, $ff) = ['A',1,'A',1,'A',1];
}

// generate ids    
$ids = [];

for($a=$aa;$a!='AA';$a++){
  for($b=$bb;$b<=9;$b++){
    $bb = 1; // reseting b - f is necessary when adding more ids
    for($c=$cc;$c!='AA';$c++){
      $cc = 'A';
      for($d=$dd;$d<=9;$d++){
        $dd = 1;
        for($e=$ee;$e!='AA';$e++){
          $ee = 'A';
          for($f=$ff;$f<=9;$f++){
            $ff = 1;

            $ids[] = "$a$b$c$d$e$f";
            // break out of all loops when desired number is reached
            if ( $numIds <= count($ids) ) { break 6; }
}}}}}}

// db setup
$conn = mysqli_connect('localhost', 'root', '', 'dbtest');
$insertstmt = mysqli_prepare($conn, 'INSERT INTO ids (id) VALUES (?)');

// insert ids
mysqli_stmt_bind_param($insertstmt, 's', $id);    
mysqli_autocommit($conn, false);
foreach ( $ids as $id ) {
  mysqli_stmt_execute($insertstmt);
}
mysqli_commit($conn);
mysqli_close($conn);


// function to increment given id, accommodates rolling over, e.g., A9 -> B1
function incc ($arr, $idx) {
  if ( is_int(intval($arr[$idx])) ) {
    if ( 9 == $arr[$idx] ) {
      $arr[$idx] = 1;
      $arr = incc($arr, --$idx); // recursing
    }
    else {
      $arr[$idx]++;
    }
  }
  else {
    if ( 'Z' === $arr[$idx] ) {
      $arr[$idx] = 'A';
      $arr = incc($arr, --$idx);
    }
    else {
      $ord = ord($arr[$idx]);
      $ord++;
      $arr[$idx] = chr($ord);
    }
  }
  return $arr;
}

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Answer 2

对于唯一和随机 ID，当您不需要顺序 ID 时：

$numIds = 20000; // how many ids do you want to generate and insert?

// db setup
$conn = mysqli_connect('localhost', 'root', '', 'dbtest');
$insertstmt = mysqli_prepare($conn, 'INSERT INTO ids (id) VALUES (?)');

// generate ids array
$ids = [];
for ($ii = 0; $ii < $numIds; $ii++) {
  do { // execute loop at least once

    // inspired by @chris85 's comment
    $id = randChr() . rand(0, 9) . randChr() . rand(0, 9) . randChr() . rand(0, 9);

  } while ( // try again if found in either db or array
    idInDb($conn, $id) || // not actually needed on first run
    (0 < count($ids) && in_array($id, $ids, true))
  );
  $ids[] = $id; // is unique, add to array
}

// insert ids
mysqli_stmt_bind_param($insertstmt, 's', $id);    
mysqli_autocommit($conn, false);
foreach ( $ids as $id ) {
  mysqli_stmt_execute($insertstmt);
}
mysqli_commit($conn);
mysqli_close($conn);


// helper functions

function randChr () { // generate random alpha character
  return chr(rand(65, 90)); // upper case only
  //return chr(rand(0, 1) ? rand(65, 90) : rand(97, 122));
  // use alternative return for upper AND lower case
}

function idInDB ($conn, $testid) { // check for id in db
  $query = "SELECT id FROM ids WHERE id = '$testid'";
  $result = mysqli_query($conn, $query);
  $found = 0 < mysqli_num_rows($result);
  mysqli_free_result($result);
  return $found;
}

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