SESSION

if(isset($_SESSION['authuser'])){
    
    echo 'Hello'.'&nbsp'.$_SESSION['authuser'].'&nbsp'.'<a href="[[~[[*id]]]]&logout">'.'LOG OUT'.'</a>';
    
}else{
    echo $modx->getChunk('form_calendar_login');
}

$chck_user = "";
$chck_pwd = "";

if(isset($_POST['logaccnt'])){
$uname = $_POST['useradmin'];
$pass = $_POST['pwdadmin'];

$select_user = $modx->query("Select username, password FROM mod_tblaccount WHERE username = '$uname' AND password = '$pass'");
foreach($select_user as $user){
$chck_user = $user['username'];
$chck_pwd = $user['password'];
}
if($chck_user == $uname && $chck_pwd == $pass){
$_SESSION['authuser'] = $chck_user;
}else{
echo '<center>Please try Again</center>';
}
}

if(isset($_GET['logout'])){
    $_SESSION['authuser'] = null;
}