PHP注册页面输入数据无法插入MySQL数据库求助

Let’s break down the common issues in your code that could be stopping user data from hitting your database, plus fixes to get it working smoothly:

1. First: Verify Your Database Connection #

Your code doesn’t check if the database connection actually succeeded. If there’s a typo in credentials, the database doesn’t exist, or MySQL isn’t running, you’ll never know without this check. Add this right after your connection line:

$db = mysqli_connect('127.0.0.1', 'root', '', 'techdrive');
// Add connection error check
if (!$db) {
    die("Database connection failed: " . mysqli_connect_error());
}

2. Catch INSERT Query Errors #

You’re running the INSERT query but not checking if it fails. Add error handling here to see exactly why the data isn’t being inserted—this will reveal issues like misspelled table/column names or permission problems:

// Replace your existing mysqli_query line with this
if (!mysqli_query($db, $query)) {
    die("INSERT failed: " . mysqli_error($db));
}

3. Fix Header Redirect Issues #

Your redirect uses a backslash (..\index.html), which acts as an escape character in PHP. Use forward slashes instead, and always add exit(); after the header to stop further code execution (this prevents unexpected behavior after redirect):

header('location: ../index.html');
exit();

4. (Bonus) Upgrade Password Security & Block SQL Injection #

MD5 is no longer a secure way to store passwords—switch to password_hash() instead. Also, using prepared statements eliminates SQL injection risks and avoids issues with special characters in usernames/emails:

Updated Secure Registration Code #

if (count($errors) == 0) {
    $password = password_hash($password_1, PASSWORD_DEFAULT); // Modern secure hashing
    // Use prepared statement to avoid injection
    $query = "INSERT INTO users (username, email, password) VALUES(?, ?, ?)";
    $stmt = mysqli_prepare($db, $query);
    mysqli_stmt_bind_param($stmt, "sss", $username, $email, $password);
    
    if (mysqli_stmt_execute($stmt)) {
        $_SESSION['username'] = $username;
        $_SESSION['success'] = "You are now logged in";
        header('location: ../index.html');
        exit();
    } else {
        die("INSERT failed: " . mysqli_stmt_error($stmt));
    }
}

And update your login code to use password_verify() instead of rehashing the input:

if (count($errors) == 0) {
    $query = "SELECT * FROM users WHERE username='$username'";
    $results = mysqli_query($db, $query);
    if (mysqli_num_rows($results) == 1) {
        $user = mysqli_fetch_assoc($results);
        if (password_verify($password, $user['password'])) {
            $_SESSION['username'] = $username;
            $_SESSION['success'] = "You are now logged in";
            header('location: ../index.html');
            exit();
        } else {
            array_push($errors, "Wrong username/password combination");
        }
    } else {
        array_push($errors, "Wrong username/password combination");
    }
}

5. Double-Check Frontend Form Fields #

Make sure your HTML form’s input name attributes match exactly what’s in your PHP:

• Username input: name="username"
• Email input: name="email"
• Password fields: name="password_1" and name="password_2"
• Signup button: name="signup"

Start with steps 1 and 2 first—they’ll immediately reveal if the problem is a broken connection or invalid SQL syntax.

内容的提问来源于stack exchange，提问作者Aroussi Riahi