为什么我的SAW（简单加法加权）无法显示结果？

Question

我想显示我的SAW代码的结果，但是当我加载它时，它仅显示“您提交的查询无效”。然后，如果我使用implode来收集$skill之类的变量，那么我将收到诸如“ unifined index skill”的错误消息。请帮助我。

这是SAW代码

    // collect skill
    $skill = array();
    $sk = $_POST["skill"];
    foreach ($sk as $sek) {
        array_push($skill, "'".$sek."'");
    }
    $skills = implode(",",$skill);

    // collect nilai
    $nilai = $this->input->post("nilai");

    //collect gaji
    $gaji = $this->input->post("gaji");

    // collect Lokasi
    $lokasi = ($this->input->post("lokasi") == "0" ? false : true);

    // collect jurusan
    $jurusan = $this->input->post("jurusan");

    $sql = $this->model_data->getRating($skills, $nilai, $gaji, $lokasi, $jurusan);

    $result = $this->db->query("$sql")->result();

    $saw = new Algoritma();
    // menambahkan Kriteria
    $saw->addCriteria("skill",$this->input->post("bobot_skill")/100,"1");
    $saw->addCriteria("nilai",$this->input->post("bobot_nilai")/100,"0");
    $saw->addCriteria("gaji",$this->input->post("bobot_gaji")/100,"0");
    $saw->addCriteria("lokasi",$this->input->post("bobot_lokasi")/100,"1");
    $saw->addCriteria("jurusan",$this->input->post("bobot_jurusan")/100,"1");


    foreach ($result as $hasil) {
        $alt = new Alternative("$hasil->kode_lowongan","$hasil->nama_perusahaan");
        $alt->addCriteria("skill",$hasil->skill);
        $alt->addCriteria("nilai",$hasil->nilai);
        $alt->addCriteria("gaji",$hasil->gaji);
        $alt->addCriteria("lokasi",$hasil->lokasi);
        $alt->addCriteria("jurusan",$hasil->jurusan);

        $saw->addAlternative($alt);
    }
    $saw->generate();
    $rekomendasi = $saw->data;
    for ($i=0; $i < count($rekomendasi); $i++) {
        for ($j=($i+1); $j < count($rekomendasi); $j++) {
            if($rekomendasi[$i]->preferensi < $rekomendasi[$j]->preferensi){
                $temp = $rekomendasi[$i];
                $rekomendasi[$i] = $rekomendasi[$j];
                $rekomendasi[$j] = $temp;
            }
        }
    }
    $data["hasil"] = $rekomendasi;
    $this->load->view("home/sawhasil",$data);
}

我使用Codeigniter进行编码。