PHP中$userInfo = $DB->getRow($query)；报错

Question

    session_start();
    
    $_SESSION["admin"] = null;
   
    $posts = $_POST;
    
    foreach ($posts as $key => $value)
    {
        $posts[$key] = trim($value);
    }
    $apassword = md5($posts["apassword"]);
    $username = $posts["aname"];
    $username="admin";    $query = "SELECT 'aname','apassword' FROM `admin` WHERE `aname` = '$aname'";
    
    $userInfo = $DB->getRow($query);    if (!empty($userInfo))
    {
        if (trim($_POST['aname']) == $username && trim($_POST['apassword']) == $apassword)
        {
            session_start();           
            $_SESSION["admin"] = true;
            header("Location:ad/index.php");
        }
        else
        {
            die("用户名密码错误");
        }
    }
    else
    {
        die("用户名密码错误");
    }

Answer 1

//$query = "SELECT 'aname','apassword' FROM `admin` WHERE `aname` = '$aname'";
$query = "SELECT aname, apassword FROM `admin` WHERE `aname` = '$aname'";