For each loop not working

I've some master categories and user groups, user groups are assigned to master categories. I am using the following code but it only display the last record in the table while I need to display all matching records.

Function in controller:

function listdesignation($id) {
    $res = $this->designation_model->GetDesignation($id);
    $this->data['test'] = $res;
    if ($res) {
        foreach ($res as $row) {
            $this->data['selected_designation'] = $this->designation_model->GetDesignation_Names($row['designation_id']);
        }
        if ($this->data['selected_designation']) {
            $this->data['enable_view'] = true;
        }
    } 
}

Function in model:

function GetDesignation_Names($id) {
    $designation = array();
    $this->db->select('*');
    $this->db->from('delta_designation');
    $this->db->where('designation_id', $id);
    $query = $this->db->get();
    if ($query->num_rows() > 0) {
        foreach ($query->result() as $row) {
            $designation[$row->designation_id]['designation_id'] = $row->designation_id;
            $designation[$row->designation_id]['designati开发者_StackOverflow中文版on'] = $row->designation;
        }
        return $designation;
    }
    return false;
}

You're overwriting your variable with each iteration through your foreach loop. You probably want to build up an array instead.

E.g. instead of

foreach (...) {
    $myvar = $row->field;
}

Try this:

$myresult = array();
foreach (...) {
    $myvar = $row->field;
    $myresult[]= $myvar;  // (append to array)
}

Then you can:

foreach ($myresult as $onerow) {
    ...
}