返回结果表单查询 - 仅显示在一行上

it's simple, but I can't do it. I have a query and I want query result to be shown only once. In my code, name of the course is shown so many times as my rows are. I use Codeigniter. My code is:

foreach ($timetable as $row) {
    echo $row->course_name;  
} 

My query is:

public function select_timetable() {

        $this->db->select('sequence_num, topic, courses_specific_id, courses_common.course_name,
        courses_specific.course_place, courses_common.courses_common_id, timetable.timetable_id');
        $this->db->from('timetable');  
        $this->db->join('courses_common', 'courses_common.courses_common_id=timetable.courses_common_id');
        $this->db->join('courses_specific', 'courses_specific.courses_common_id=courses_common.courses_common_id');

        $this->db->where('courses_specific_id', $this->input->post('courses_specific_id'));
        $result=$this->db->get();
              return $result->result();
    }

And the result of var_dump($timetable[0]) is:

object(stdClass)#27 (7) { 
    ["sequence_num"]=> string(1) "1" 
    ["topic"]=> string(10) "HTML tags " 
    ["courses_specific_id"]=> string(1) "1" 
    ["course_name"]=> string(4) "HTML" 
    ["course_place"]=> string(6) "Center" 
    ["courses_common_id"]=> string(1) "1" 
    ["timetable_id"]=> string(1) "1" 
} 

HTMLobject(stdClass)#27 (7) { 
    ["sequence_num"]=> string(1) "1" 
    ["topic"]=> string(10) "HTML tags " 
    ["courses_specific_id"]=> string(1) "1" 
    ["course_name"]=> string(4) "HTML"
    ["course_place"]=> string(6) "Center"
    ["courses_common_id"]=> string(1) "1" 
    ["timetable_id"]=> string(1) "1" 
} 

HTMLobject(stdClass)#27 (7) { 
    ["sequence_num"]=> string(1) "1" 
    ["topic"]=> string(10) "HTML tags "
    ["courses_specific_id"]=> string(1) "1" 
    ["course_name"]=> string(4) "HTML" ["course_place"]=> string(6) "Center" ["courses_common_id"]=> string(1) "1" ["timetable_id"]=> string(1) "1" } HTML

To access the the results you have to do something like:

<?php
foreach ($timetable->result() as $row)
{      
 echo $row->course_name;  
} 
?>

If you wanted to only show one row you would need to do something like:

if ($timetable->num_rows() > 0)
{
$row = $timetable->row_array(); 
  echo $row['course_name'];
}

You can also walk through your different rows like:

$row = $timetable->first_row()
$row = $timetable->last_row()
$row = $timetable->next_row()
$row = $timetable->previous_row()