如果在包含文件中使用连接，则 Jquery ajax 调用不起作用

Question

如果我在包含 php 文件上使用连接，我无法弄清楚为什么 jquery ajax 后调用不起作用，尽管我从 php 得到了正确的响应。请告诉我这背后的解释是什么

这是在我的数据库文件中

<?php

$host = "mysql2.000webhost.com"; 
$username = "a212_mt5199";
$password = "secret";
$db = "a211_mydb";

$con = new mysqli ($host, $username, $password, $db);

GLOBAL $con;

if ($con->connect_error) {
    die ("Error:" . $con->connect_error);
}

?>  

这个包括上面的不起作用

<?php

include("db.php");

// set parameters and execute
$myusername=$_POST['name']; 
$mypassword=$_POST['pwd']; 

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);

$stmt = $con->prepare("SELECT username, password FROM members WHERE username=? and password=?");
$stmt->bind_param("ss", $myusername, $mypassword);

$stmt->execute();
$stmt->bind_result($username, $password);
$stmt->store_result();

// Mysql_num_row is counting table row
$count=$stmt->num_rows;

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
    // Register $myusername, $mypassword and redirect to file "login_success.php"
    session_register("myusername");
    session_register("mypassword"); 
    echo 'true';
    $_SESSION['user_name']= $username;
} else {
    echo "Wrong Username or Password";
}

$stmt->close();
$con->close();

?>

这是有效的

<?php

$host = "mysql2.000webhost.com"; 
$username = "a212_mt5199";
$password = "secret";
$db = "a211_mydb";

$con = new mysqli ($host, $username, $password, $db);

if ($con->connect_error) {
    die ("Error:" . $con->connect_error);
}

// set parameters and execute
$myusername=$_POST['name']; 
$mypassword=$_POST['pwd']; 

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);

$stmt = $con->prepare("SELECT username, password FROM members WHERE username=? and password=?");
$stmt->bind_param("ss", $myusername, $mypassword);

$stmt->execute();
$stmt->bind_result($username, $password);
$stmt->store_result();

// Mysql_num_row is counting table row
$count=$stmt->num_rows;

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
    // Register $myusername, $mypassword and redirect to file "login_success.php"
    session_register("myusername");
    session_register("mypassword"); 
    echo 'true';
    $_SESSION['user_name']= $username;
} else {
    echo "Wrong Username or Password";
}

$stmt->close();
$con->close();

?>

Answer 1

能够通过使用 DEFINE 变量来解决问题。