Php mysqli转换获取查询

如何将此语句转换为mysqli。我尝试转换它，但不起作用。我错过了什么。我想连接到登录表单

这是我转换的代码

<?php
include('admin/dbcon.php');
        session_start();
        $username = $_POST['username'];
        $password = $_POST['password'];

        /* teacher */
        $query_teacher = mysql_query("SELECT * FROM teacher WHERE username='$username' AND password='$password'")or die(mysql_error());
        $num_row_teacher = mysql_num_rows($query_teacher);
        $row_teahcer = mysql_fetch_array($query_teacher);

        /* admin */
        $query_admin = mysql_query("SELECT * FROM users WHERE username='$username' AND password='$password'")or die(mysql_error());
        $num_row_admin = mysql_num_rows($query_admin);
        $row_admin = mysql_fetch_array($query_admin);


         if ($num_row_teacher > 0){
        $_SESSION['id']=$row_teahcer['teacher_id'];
        echo 'true';

        }else if ($num_row_admin > 0){
        $_SESSION['id']=$row_admin['user_id'];
        echo 'true_admin';

         }else{ 
                echo 'false';
        }   

        ?>

缺少您的

$row_teahcer=mysqli_fetch_array($num_row_teacher);
$row_admin=mysqli_fetch_array( $num_row_admin);

您缺少
$results=$num_row_teacher->fetch（）$结果2=$num_row_admin->fetch（）
在设置之后，
$\u SESSION['id']=$results['user\u id']
@Shahmee这不是OOP的过程。将其替换为
$results=mysqli\u fetch\u数组（$num\u row\u teacher）$results2=mysqli\u fetch\u数组（$num\u row\u admin）
@Shahmee
mysqli_fetch_数组
将只返回一个结果。如果OP的表包含多个用户，则需要使用while循环。非常感谢。我得到了正确的线索。但挑战在于，当我将文件上传到我的网站时，我无法添加、编辑或修改任何数据。但我可以在本地主机服务器上完成所有这些。可能有什么问题
 <?php
//db details
$dbHost = 'localhost';
$dbUsername = 'root';
$dbPassword = '';
$dbName = 'retreat';

//Connect and select the database
$db = new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);

if ($db->connect_error) {
    die("Connection failed: " . $db->connect_error);
}

            session_start();
            $username = $_POST['username'];
            $password = $_POST['password'];



            /* teacher */
            $query = $db->query("SELECT * FROM teacher WHERE username='$username' AND password='$password'")or die(mysqli_error());
            $num_row_teacher = mysqli_num_rows($query);
            $row_teahcer = mysqli_fetch_array($query);



            /* admin */
            $query_admin = $db->query("SELECT * FROM users WHERE username='$username' AND password='$password'")or die(mysqli_error());
            $num_row_admin = mysqli_num_rows($query_admin);
            $row_admin = mysqli_fetch_array($query_admin);


             if ($num_row_teacher > 0){
            $_SESSION['id']=$row_teahcer['teacher_id'];
            echo 'true';

            }else if ($num_row_admin > 0){
            $_SESSION['id']=$row_admin['user_id'];
            echo 'true_admin';

             }else{ 
                    echo 'false';
            }   


    enter code here
        ?>

$row_teahcer=mysqli_fetch_array($num_row_teacher);
$row_admin=mysqli_fetch_array( $num_row_admin);