错误检查将数据插入codeigniter中的数据库

Question

i have form in put input fleet ID and multiple check unit ID. but in one date just use one unit_id.

i check with this code but data can not insert.

$fleet = $this->input->post('id_fleet');
$unit_id = $this->input->post('unit_id');

$records = array();

for ($i=0; $i < count($unit_id) ; $i++) { 
    $records[] = array('id_fleet' => $fleet,
                    'unit_id' => $unit_id[$i]);
}

$query = $this->database_three->query("select count(id_fleet_member) as unit from fleet_member  where id_fleet = '$fleet' AND unit_id = '$unit_id' group by fleet_member.id_fleet");
$ans = $query->row();

$check = $this->database_three->query("select fleet.fleet_status, fleet_member.unit_id from fleet Left join fleet_member 
                on fleet.id_fleet=fleet_member.id_fleet AND fleet_member.unit_id = '$unit_id' AND fleet.fleet_status = '$id_fleet'");

if ($ans->unit > 0) {
    $this->session->set_flashdata('message', generateErrorMessage('Data Fleet ID Sudah Digunakan'));
    redirect(site_url('fleet_member'));     
} else {
    if ($check == FALSE) {
        foreach ($records as $data) {
            $query = "insert into fleet_member (id_fleet, unit_id) values ('".$data['id_fleet']."','".$data['unit_id']."')"; 
            $this->database_three->query($query);
        }
        $this->session->set_flashdata('message', generateSuccessMessage('Data berhasil ditambah'));
        redirect(site_url('fleet_member'));
    } else {
        $this->session->set_flashdata('message', generateErrorMessage('Data Unit ID Sudah Digunakan'));
        redirect(site_url('fleet_member'));
    }
}

Can you tell me how to solved this problem?

thank you,