login.php sql數據庫

Question

我的login.php文件加載時出現此錯誤。“警告：mysql_num_rows（）：提供的參數不是有效的MySQL結果資源”這就是我所擁有的。

$query = mysql_query("SELECT * FROM users WHERE username='$username'");
$numrows = mysql_num_rows($query);
if($numrows!=0)
{
while ($row = mysql_fetch_assoc($query))
{
    $dbusername = $row['username'];
    $dbpassword = $row['password'];
}
if ($username==$dbusername&&$password==$dbpassword)
{
    echo "Youre in!";
}
else
    echo "Incorrect Password!";
}
else
    die("That user doesnt exist!");
}
else
die("Please enter a username and a password!");
?>

Answer 1

將此添加到文件的頂部

ini_set('display_errors', 'on');
error_reporting(E_ALL | E_STRICT);

此“應”顯示您的語法錯誤，無論如何，您的問題是語法錯誤

以下代碼應使您更接近最終目的地

<?
ini_set('display_errors', 'on');
error_reporting(E_ALL | E_STRICT);

if($username) {
    $query = mysql_query("SELECT * FROM users WHERE username='$username'");
    $numrows = mysql_num_rows($query);
    if($numrows!=0) {
        while ($row = mysql_fetch_assoc($query)) {
            $dbusername = $row['username'];
            $dbpassword = $row['password'];
        }

        if ($username==$dbusername&&$password==$dbpassword) {
            echo "Youre in!";
        } else {
            echo "Incorrect Password!";
        }
    } else {
        die("That user doesnt exist!");
    }
} else {
    die("Please enter a username and a password!");
}

Answer 2

您錯過了一些花括號：

$query = mysql_query("SELECT * FROM users WHERE username='$username'");
$numrows = mysql_num_rows($query);
if($numrows!=0)
{
    while ($row = mysql_fetch_assoc($query))
    {
        $dbusername = $row['username'];
        $dbpassword = $row['password'];
    }
    if ($username==$dbusername&&$password==$dbpassword)
    {
        echo "Youre in!";
    }
    else
        echo "Incorrect Password!";
    }
} else // <- THIS ONE
    die("That user doesnt exist!");
}
// And here another, in a if condition that isn't started in the code you give.
else
die("Please enter a username and a password!");
?>

可以將服務器配置為：如果出現錯誤，則該頁面為空白。

mySQL登錄的其他一些技巧： 永遠不要將用戶輸入直接放在MySQL查詢語句中！ 這樣就很容易通過SQL注入來入侵您的網站。

有關更多詳細信息，請訪問： http : //www.derby-web-design-agency.co.uk/blog-post/how-to-create-a-secure-login-system-in-php-part-1/12/