Question

我对PHP和MySQL还是很陌生，我只是想不通。我在论坛周围搜索了所有内容，但没有找到我能理解的答案。希望有人可以向我解释我的代码发生了什么。

英雄是我的代码的一部分：

$con = mysqli_connect($DATABASE_HOST, $DATABASE_USER, $DATABASE_PASS, 
$DATABASE_NAME);
if ( mysqli_connect_errno() ) 
{
    // If there is an error with the connection, stop the script and display the error.
    die ('Failed to connect to MySQL: ' . mysqli_connect_error());
}
// Now we check if the data from the login form was submitted, isset() will check if the data exists.
if (!isset($_POST['username']) ) 
{
    // Could not get the data that should have been sent.
    die ('Please fill both the username  field!');
}

if (isset($_POST['username'])) 
{
    $username = mysqli_real_escape_string($con, trim($_POST["username"]));
    $password = mysqli_real_escape_string($con, trim($_POST['password']));
    echo $password;
    $result = mysqli_query($con, "SELECT * FROM users WHERE username = '" . $username. "' and pass = '" . md5($password). "'");
    if ($row = mysqli_fetch_assoc($result)) 
    {
        //$_SESSION['user_id'] = $row['uid'];
        //$_SESSION['user_name'] = $row['user'];
        header("Location: home.php");
    } else {
        $error_message = "Incorrect username or Password!!!";
    }
}

我的索引文件：

<form action="authenticate.php" method="post">
                <label for="username">
                    <i class="fas fa-user"></i>
                </label>
                <input type="text" name="username" placeholder="Username" id="username" required>
                <label for="password">
                    <i class="fas fa-lock"></i>
                </label>
                <input type="password" name="password" placeholder="Password" id="password" required>
                <input type="submit" name = "login " value="login">
            </form>

Answer 1

如果mysqli_query（）查询失败，它将返回false而不是结果。因此会引发此错误。

“warning ,mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given”

如果查询失败，您必须添加额外的检查，以获取错误并查看查询出了什么问题

$result = mysqli_query($con, "SELECT * FROM users WHERE username = '" . $username. "' and pass = '" . md5($password). "'");


if (!$result) {
    echo "SQLSTATE error: " . mysqli_sqlstate($con);
    echo "<br>";
    echo "SQLSTATE error: " . mysqli_error($con);
    exit;
}

if ($row = mysqli_fetch_assoc($result)) 
    {
        //$_SESSION['user_id'] = $row['uid'];
        //$_SESSION['user_name'] = $row['user'];
        header("Location: home.php");
    } else {
        $error_message = "Incorrect username or Password!!!";
    }

这样您就可以看到错误。

“警告，mysqli_fetch_assoc（）期望参数1为mysqli_result，给定布尔值”，为什么？

1 个答案: