没有错误消息的PHP SQL错误

Question

 -- register.php --
<form id='form' action="../function/process_reg.php" method="post">
  <input type="text" class="form-control" name="id" id="form-title" placeholder="ID">
  <input type="password" class="form-control" name="pw" id="form-title" placeholder="PASSWORD">
  <input type="text" class="form-control" name="nickname" id="form-title" placeholder="NICKNAME">
  <input type="submit" name="name" class="btn btn-default btn-lg" value='회원가입'>

 -- process_reg.php --
 <?php
  require("../config/config.php");
  require("../lib/db.php");
  require("../lib/password.php");
  require("../lib/codegen.php");
  $conn = db_init($config["host"],$config["duser"],$config["dpw"],$config["dname"]);

  $id = $_POST['id'];
  $nickname = $_POST['nickname'];
  $sql = 'INSERT INTO userdata (id,pw,nickname,pid) VALUES("'.$id.'","'. password_hash($_POST['pw'], PASSWORD_DEFAULT).'", "'.$nickname.'",.generateRenStr(10).)';
  $result = mysqli_query($conn, $sql);
  header('Location: ../login/login.php');
?>

 -- config.php --
 <?php
   $config = array(
     "host" => 'localhost',
     "duser" => 'root',
     "dpw" => "B32bpu98",
     "dname" => "sid_userdata",
   );
 ?>

 -- db.php --
 <?php
   function db_init($host, $duser, $dpw, $dname){
     $conn = mysqli_connect($host,$duser,$dpw);
     mysqli_select_db($conn, $dname);
     return $conn;
   }
 ?>

 -- codegen.php --
 <?
   function generateRenStr($length) {
     echo 'helloworld';
     $character = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
     $rendom_str = "";
     $loopNum = $length;
     while ($loopNum--) {
       $rendom_str .= $character(mt_rand(0, strlen($character)));
     }
     return $rendom_str;
   }
 ?>

此代码在浏览器上不会出现错误，但它不会向sql server发送数据。我无法找到它发生的原因。我认为codegen.php有错误。我没有编写codegen.php和password.php。所以我无法修复它。

• password.php太长了，无法写在这里。