Codeigniter $this->db->order_by(' ','desc') result is not complete

Question

I want to sort my database values in descending order using this query below in my model. However, it doesn't completely sort in descending order all the values in the database but when ascending is used, it works well.

function sort_all_courses_desc($tennant_id)
{
    $this->db->select('*');
    $this->db->where('tennant_id',$tennant_id);
    $this->db->order_by("course_name","desc");
    $this->db->from('courses');
    $query=$this->db->get();
    return $query->result();
}

Answer 1

Put from before where, and order_by on last:

$this->db->select('*');
$this->db->from('courses');
$this->db->where('tennant_id',$tennant_id);
$this->db->order_by("UPPER(course_name)","desc");

Or try BINARY:

ORDER BY BINARY course_name DESC;

You should add manually on codeigniter for binary sorting.

And set "course_name" character column.

If sorting is used on a character type column, normally the sort is conducted in a case-insensitive fashion.

What type of structure data in courses table?

If you frustrated you can put into array and return using PHP:

Use natcasesort for order in "natural order": (Reference: http://php.net/manual/en/function.natcasesort.php)

Your array from database as example: $array_db = $result_from_db:

$final_result = natcasesort($array_db);

print_r($final_result);

Answer 2

$this->db1->where('tennant_id', $tennant_id);
$this->db1->order_by('id', 'DESC');
return $this->db1->get('courses')->result();

Answer 3

Put the line $this->db->order_by("course_name","desc"); at top of your query. Like

$this->db->order_by("course_name","desc");$this->db->select('*');
$this->db->where('tennant_id',$tennant_id);
$this->db->from('courses');
$query=$this->db->get();
return $query->result();