show the values in dropdown from database while updating a record

[MtR_1]

while updating my form it retrieves all info from db in respective field but unable to display values in dropdowns

this is my controller for update

function update($a_id)
    {
        $data['a_id'] = $a_id;

        $data['sector'] = $this->sf_model->get_sector();
        $data['subsector'] = $this->sf_model->get_subsector();
        $data['type'] = $this->sf_model->get_type();
        $data['view'] = $this->sf_model->get_account_record($a_id);

        $this->form_validation->set_rules('a_name', 'Account Name', 'trim|required|xss_clean|callback_alpha_only_space');
        $this->form_validation->set_rules('a_web', 'Website', 'trim|required|xss_clean');


        if ($this->form_validation->run() == FALSE)
        {
            $this->load->view('viewUpdate', $data);
        }
        else
        {
            $data = array(
                'a_id' => $this->input->post('a_id'),
                'a_name' => $this->input->post('a_name'),
                'a_website' => $this->input->post('a_web'),
                't_id' => $this->input->post('a_type'),
                's_id' => $this->input->post('a_sector'),
                'ss_id' => $this->input->post('a_subsector'),
                'a_billingStreet' => $this->input->post('a_billingStreet'),
                'a_billingCountry' => $this->input->post('a_billingCountry'),
                'a_mobile' => $this->input->post('a_mobile'),

            );
            $this->db->where('a_id', $_POST['a_id']);
            $this->db->update('account_info', $data);


            $this->session->set_flashdata('msg','<div class="alert alert-success text-center">Successfully Updated!</div>');
            redirect('salesforce' . $a_id);
        }

    }

this is my model

function get_account_record($a_id)
    {
        $this->db->where('a_id', $a_id);
        $this->db->from('account_info');
        $query = $this->db->get();
        return $query->result();
    }
function get_type()
    {
        $results = $this->db->select('t_id, t_name')->from('account_type')->get()->result();

        $t_id = array('-SELECT-');
        $t_name = array('-SELECT-');

        for ($i = 0; $i < count($results); $i++)
        {
            array_push($t_id, $results[$i]->t_id);
            array_push($t_name, $results[$i]->t_name);
        }
        return $type_result = array_combine($t_id, $t_name);
    }
 function get_sector()
    {
        $results = $this->db->select('s_id, s_name')->from('account_sector')->get()->result();

        $s_id = array('-SELECT-');
        $s_name = array('-SELECT-');

        for ($i = 0; $i < count($results); $i++)
        {
            array_push($s_id, $results[$i]->s_id);
            array_push($s_name, $results[$i]->s_name);
        }
        return $sector_result = array_combine($s_id, $s_name);
    }
    function get_subsector()
    {
        $results = $this->db->select('ss_id, ss_name')->from('account_subsector')->get()->result();

        $ss_id = array('-SELECT-');
        $ss_name = array('-SELECT-');

        for ($i = 0; $i < count($results); $i++)
        {
            array_push($ss_id, $results[$i]->ss_id);
            array_push($ss_name, $results[$i]->ss_name);
        }
        return $subsector_result = array_combine($ss_id, $ss_name);
    }

this is the view

<div class="form-group"> <div class="row colbox"> <div class="col-lg-4 col-sm-4"> <label for="a_id" class="control-label">Account ID</label> </div> <div class="col-lg-8 col-sm-8"> <input id="a_id" name="a_id" placeholder="" readonly="readonly" type="text" class="form-control"  value="<?php echo $view[0]->a_id; //$a_id;?>" /> <span class="text-danger"><?php echo form_error('a_id'); ?></span> </div> </div> </div> <div class="form-group"> <div class="row colbox"> <div class="col-lg-4 col-sm-4"> <label for="a_name" class="control-label">Account Name</label> </div> <div class="col-lg-8 col-sm-8"> <input id="a_name" name="a_name" placeholder="Enter Account Name" type="text" class="form-control"  value="<?php echo $view[0]->a_name; ?>" /> <span class="text-danger"><?php echo form_error('a_name'); ?></span> </div> </div> </div> <div class="form-group"> <div class="row colbox"> <div class="col-lg-4 col-sm-4"> <label for="a_type" class="control-label">Type</label> </div> <div class="col-lg-8 col-sm-8"> <?php
                            $attributes = 'class = "form-control" id = "a_type"';
                            echo form_dropdown('a_type',$type,set_value('a_type'),$attributes);?> <span class="text-danger"><?php echo form_error('a_type'); ?></span> </div> </div> </div> <div class="form-group"> <div class="row colbox"> <div class="col-lg-4 col-sm-4"> <label for="a_sector" class="control-label">Sector</label> </div> <div class="col-lg-8 col-sm-8"> <?php
                            $attributes = 'class = "form-control" id = "a_sector"';
                            echo form_dropdown('a_sector',$sector,set_value('a_sector'),$attributes);?> <span class="text-danger"><?php echo form_error('a_sector'); ?></span> </div> </div> </div> 

Does your markup really look like that?