CodeIgniter MySQL query not working

Question

I'm trying to get this query to work in CodeIgniter but it's spitting out an error:

A Database Error Occurred Error Number: 1096

No tables used

SELECT *

If I put the query directly into MySQL it works fine (I replace the $variables with values). Here is the query as input into codeigniter:

$this->db->query(" 
    SELECT * 
    FROM writing_quests 
    LEFT OUTER JOIN members_quests_completed 
    ON members_quests_completed.quest_id = writing_quests.id 
    WHERE writing_quests.level_required <=  $userlevel 
    AND ( 
        members_quests_completed.user_id = $user_id
        OR 
        members_quests_completed.user_id IS NULL )"
);
$query = $this->db->get();

Am I doing something that is wrong and I am missing it? I've included the whole function call in case the problem is somewhere else? I've done this exact thing many times without an issue.

function get_all_quests_for_user() {
    $user_id = $this->session->userdata('user_id');
    $userlevel = $this->session->userdata('user_level');

    $this->db->query("SELECT writing_quests.id, writing_quests.points_availible, writing_quests.name, writing_quests.note, writing_quests.instructions, writing_quests.time_limit, members_quests_completed.location_completed, members_quests_completed.status  FROM writing_quests LEFT OUTER JOIN members_quests_completed ON members_quests_completed.quest_id = writing_quests.id WHERE writing_quests.level_required <=  '$userlevel' AND writing_quests.unlocked = 1 AND ( members_quests_completed.user_id = '$user_id' OR members_quests_completed.user_id IS NULL )");
    $query = $this->db->get();
    $this->db->last_query();
    return $query->result();
}

Answer 1

SELECT writing_quests.*, ( put needed fields from members_quests_completed ) 
FROM writing_quests
LEFT JOIN members_quests_completed ....

same fields names corrupting results column's names in result object

FYI it not wise to use *, you should have list of fields...
and what is most important:

$result = $this->db->query ( ... );

$this->db->query ( ... ) is good when INSERT or UPDATE (mostly), when you pulling data assign results to variable: http://codeigniter.com/user_guide/database/results.html

Answer 2

I think it should be like this:

$query = $this->db->query(" 
SELECT * 
FROM writing_quests 
LEFT OUTER JOIN members_quests_completed 
ON members_quests_completed.quest_id = writing_quests.id 
WHERE writing_quests.level_required <=  $userlevel 
AND ( 
    members_quests_completed.user_id = $user_id
    OR 
    members_quests_completed.user_id IS NULL )"
);

Or:

$query = $this->db->get('mytable');