Генератор уникальных id. (строчные, прописные, цифры)

  $chars = 'abdefhiknrstyzABDEFGHKNQRSTYZ1234567890';
  $numChars = strlen($chars);
  $string = '';
  for ($i = 0; $i < $length; $i++) {
    $string .= substr($chars, rand(1, $numChars) - 1, 1);
  }

$array = array("a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","P","Q","R","S","T","U","V","W","X","Y","Z","1","2","3","4","5","6","7","8","9","0");
for ($i=0; $i<8; $i++){
  $r = rand(0,60);
  $n[$i]= $array["$r"];
}
$key = $n[0].$n[1].$n[2].$n[3].$n[4].$n[5].$n[6].$n[7];

  $key = ''; 
$array = array_merge(range('A','Z'),range('a','z'),range('0','9')); 
$c = count($array); 
for($i=0;$i<8;$i++) {$key .= $array[rand(0,$c)];} 
 
$seed = str_split('abcdefghijklmnopqrstuvwxyz'
                 .'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                 .'0123456789'); // and any other characters
shuffle($seed); // probably optional since array_is randomized; this may be redundant
$rand = '';
foreach (array_rand($seed, 5) as $k) $rand .= $seed[$k];
 
substr(str_shuffle(str_repeat("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", 5)), 0, 8);