Issue with php mysql login $_POST['username'] = $res - Issue with php mysql login $_POST['username'] = $result['username']

Issue with php mysql login $_POST['username'] = $result['username']

我是初学者，我已经从0开始编写了自己的PHP登录，但我仍然有一些错误，下面是代码:

        <?php 
    include 'connection.php';
    $query = " SELECT * FROM admin";
    $result = mysql_query($query) or die(mysql_error());
    ?>
    <form action="<?php echo $_SERVER['SELF_PHP']; ?>" method="post">
        Username : <input type="text" name="usernameInput" value="" />
        Password : <input type="password" name="passwordInput" value="" />
                    <input type="submit" value="Login" />
    </form>
    <?php
    $username = $_POST['usernameInput'];
    $password = $_POST['passwordInput'];
    if ($username = $result['username']) {
        if ($password = $result['password']){
            header('Location: admin.php');
        } else {
            echo "PASSWORD IS INCORRECT";
        }
    } else {
        echo "USERNAME IS INCORRECT";
    }
    ?>

所以如果你能解决这个问题，或者从PHP登录中得到一个更简单的方法，请告诉我。:)

几件事…

不要使用mysql函数
您需要使用==来比较字符串，而不是=

你需要实际获取你的查询结果

include 'connection.php';
$query = " SELECT * FROM admin";
$result = mysql_query($query) or die(mysql_error()); 
$row = mysql_fetch_row($result); /* add this */
?>
<form action="<?php echo $_SERVER['SELF_PHP']; ?>" method="post">
    Username : <input type="text" name="usernameInput" value="" />
    Password : <input type="password" name="passwordInput" value="" />
                <input type="submit" value="Login" />
</form>
<?php
if(isset($_POST['usernameInput']) && isset($_POST['passwordInput'])){
    $username = $_POST['usernameInput'];    
    $password = $_POST['passwordInput'];
}
else{
   echo 'some error ...';
}
if($username == $row ['username'] && $password == $row ['password']){
    header('Location: admin.php');
} 
else{
    echo ' username or password is wrong';
}
?>

我必须指出你没有先检查邮件就一次又一次地发送相同的表单。当你发送表单时，你将无法发送头重定向，因为html已经启动并且头已经发送了。

Mysql函数已弃用，请使用mysqli接口。

在其他几个错误中，如assignment =而不是is equal ==

试试这样:

如果没有post存在，发送表单else检查，如果ok则重定向或不ok。重新发送表单

<?php 
if($_POST){
    include 'connection.php';
    $query = " SELECT * FROM admin";
    $r = mysql_query($query) or die(mysql_error());
    // get an associated array from query result resource. 
    $result = mysql_fetch_assoc($r);  
    $username = $_POST['usernameInput'];
    $password = $_POST['passwordInput'];
    if (  ($username == $result['username'])
       && ($password == $result['password'])){
        header('Location: admin.php');
        exit(0);
    } else {
        echo "PASSWORD IS INCORRECT";
    }
} 
?>
<form action="<?php echo $_SERVER['SELF_PHP']; ?>" method="post">
    Username : <input type="text" name="usernameInput" value="" />
    Password : <input type="password" name="passwordInput" value="" />
                <input type="submit" value="Login" />
</form>
<?php
?>