Mysql query using order by and group by clause for highest qualification

Question

I want to get user highest education details in descending order instead of all education details, so I am joining user table with education details table, but query which I written using group by and order by clause even it is not working as per my expectation.

 table  users:
    
    id   name
    
    1    aaa
    
    2    bbb
    
    3    ccc

table education_details

    eid  user_id   course_id    course type
    
    1    1        12           graduation
    
    2    1        13           post_graduation
    
    3    2        18           graduation
    
    4    2        20           post_graduation

Expected output:

user_id   eid             course_type

2          4             post_graduation

1          2             post_graduation

Query:

$this->db->select('u.id as user_id,e.eid,e.course_type');
$this->db->from('users u');
$this->db->join('education_details e','e.user_id=u.id','left');
$this->db->order_by('e.id','desc');
$this->db->group_by('e.user_id');
$this->db->get()->result();