Help tuning a very poor SQL query

[eluser]Leon Stafford[/eluser]
OK, not using JOIN, but this is working a treat!

Code:

function get_kanjisearch_list($level = 1, $isShuffled = false)
    {
        
        $user = $this->db_session->userdata('id');
      
        
        if ($isShuffled)
        {
            //
        }
        else
        {
          
            
            $query = $this->db->query("            
            SELECT *
            FROM kg_compounds
            WHERE NOT
            EXISTS (
                SELECT compound
                FROM kg_progress
                WHERE kg_progress.compound = kg_compounds.id AND
                (
                kg_progress.compound_progress =1 AND kg_progress.user = '$user'
                )
            
            )
            AND grade = '$level'
            
            LIMIT 20
            
            ");
            
            
        }
        
        
        $compound_list = array();

        foreach ($query->result() as $row)
        {
            
                            $compound_list[] = array(    'id' => $row->id,
                                                'compound' => $row->compound,
                                                'reading' => $row->reading,
                                                'meaning' => $row->meaning,
                                                'grade' => $row->grade,
                
                                            );    
                    
                
        }
        
        
        return $compound_list;
    
    }

Next, I will implement the better random() methods mentioned in the above posts