检查sql查询和if语句

Question

I have such problem. I have a list about courses that I'm signed up

http://girlsdoit.pl/agenda/IT

If I'm signed up I get a value "jesteś już zapisany" I would like that if I'm not signed up I get a path to sign up button

In a table "registration" I have columns "user_uid" which I would like to compare with logged in user and entity_id which I would like to compare with $data->nid

    <?php
    global $user;
    $uid=$user->uid;
    $result = db_query('SELECT n.entity_id, n.user_uid
    FROM {registration} n WHERE n.user_uid = :uid', array(':uid' => $uid));

    foreach ($result as $record) {
    if (($record->user_uid==$uid) AND ($record->entity_id==$data->nid) ){
    echo "jesteś już zapisany";
    }
    elseif (($record->user_uid!=$uid))
     {
      $path=drupal_get_path_alias('node/'.$data->nid);
      echo $path;
     }
    }
    ?>

Answer 1

According to Drupal 7 API documentation, when a user is not logged-in the attribute "uid" in global object "$user" is zero. You do not need to perform a database search to check if the user is logged-in or not.