Codeigniter：函数中的位置

Question

So I have this MySQL Query, Can you please help me to convert this into codeigniter way?

select * 
  from projectskillslist ps
  LEFT 
  JOIN empskillslist s 
    ON s.skillsID = ps.skillsID
  LEFT 
  JOIN projects p 
    ON p.projectID = ps.projectID
  where ps.skillsID IN (SELECT skillsID 
                          FROM  empwithskills 
                         where empID='test');

I have tried this, but It didn't work they wway I wanted to.

$this->db->select("*");
        $this->db->from('projectskillslist ps');
        $this->db->join('empskillslist s', 's.skillsID = ps.skillsID', 'left');
        $this->db->join('projects p', 'p.projectID = ps.projectID', 'left');
        $this->db->where('ps.skillsID');
        $this->db->where_in("(SELECT skillsID FROM  empwithskills where empID='$username')");
        $query = $this->db->get();
        $result = array();
        if ($query->num_rows() > 0) {
            foreach ($query->result_array() as $row) {
                $result[] = $row;
            }
            return $result;
        }
        return false;

Answer 1

If the query was like this, could you figure out how to rewrite it in codeigniter...

select ps.name
     , s.the
     , p.rojects
     , y.ou
     , a.ctually
     , w.ant 
     , r.eturned 
  from projectskillslist ps
  LEFT 
  JOIN empskillslist s 
    ON s.skillsID = ps.skillsID
  LEFT 
  JOIN projects p 
    ON p.projectID = ps.projectID
  JOIN empwithskills x
    ON x.skillsID = ps.skillsID 
 where x.empID = 'test';