如何在不同页面中调用fetch查询函数（PHP）

我已经编写了以下代码，数据无法提取。有人能帮我吗。我主要做程序编程，所以我对oops没有那么多知识

1.xyzconfig.php 2.dbconnect.php 3.function.php

---

functions.php需要包含dbconnect.php而不是xyzconfig.php

include_once 'dbconnect.php';   

 function user_fetch($mysqli)

{

    if($stmt=$mysqli->prepare("SELECT id, username,email,role FROM members"))
    {
        $stmt->execute();   

        $stmt->store_result();

         if($stmt->num_rows >= 1)

         {

          while($row=$stmt->fetch_assoc() )
          {

            echo "<tr><td>".$row["id"]."</td><td>".$row["username"]." ".$row["email"]." ".$row['role']."</td></tr>";

          }

        }    
    }}

---

使用这两个store_result（）绝对没有意义，我这样做了，但仍然没有获取检查您的SQL

include_once 'xyzconfig.php';   

$mysqli = new mysqli(HOST, USER, PASSWORD, DATABASE);

if($mysqli->connect_error) 

{

header("Location: ../error.php?err=Unable to connect to MySQL");

exit();

}

include_once 'xyzconfig.php';   

 function user_fetch($mysqli)

{

    if($stmt=$mysqli->prepare("SELECT id, username,email,role FROM members"))
    {
        $stmt->execute();   

        $stmt->store_result();

         if($stmt->num_rows == 1)

         {

          while($row=$stmt->fetch_assoc() )
          {

            echo "<tr><td>".$row["id"]."</td><td>".$row["username"]." ".$row["email"]." ".$row['role']."</td></tr>";

          }

        }    
    }}

include_once 'includes/db_connect.php';

include_once 'includes/functions.php';

echo user_fetch($mysqli);

include_once 'dbconnect.php';   

 function user_fetch($mysqli)

{

    if($stmt=$mysqli->prepare("SELECT id, username,email,role FROM members"))
    {
        $stmt->execute();   

        $stmt->store_result();

         if($stmt->num_rows >= 1)

         {

          while($row=$stmt->fetch_assoc() )
          {

            echo "<tr><td>".$row["id"]."</td><td>".$row["username"]." ".$row["email"]." ".$row['role']."</td></tr>";

          }

        }    
    }}

include_once 'includes/dbconnect.php';

include_once 'includes/functions.php';

echo user_fetch($mysqli);