不唯一的表/别名：'siswa' 错误号：1066 Codeigniter

Question

i have eror in my scirpt, i just want to show siswa detail data

Error Number: 1066

Not unique table/alias: 'siswa'

SELECT * FROM ( kelas , siswa ) JOIN siswa ON siswa . kelas_id = kelas . id WHERE nis = '1001'

Filename: C:/xampp/htdocs/konsultasi/system/database/DB_driver.php

Line Number: 691

My Controller:

public function siswa_detail($id)
  {
    $detail = $this->m_datas->detail_data($id);
    $data['detail'] = $detail;

    $this->load->view('templates/header');
    $this->load->view('v_bk/view_siswa_detail', $data);
    $this->load->view('templates/footer');
  }

My Models:

public function detail_data($id = NULL)
    {
        $this->db->select('*');
        $this->db->from('siswa');
        $this->db->join('kelas', 'siswa.kelas_id = kelas.id');
        $query = $this->db->get_where('siswa', array('nis' => $id))->row();
        return $query;
    }

Answer 1

you have to delete $this->db->from('siswa')

    public function detail_data($id = NULL)
    {
        $this->db->select('*');
        $this->db->join('kelas', 'siswa.kelas_id = kelas.id');
        $query = $this->db->get_where('siswa', array('nis' => $id))->row();
        return $query;
    }

and It is good to insert 'left' or 'right' in join.

$this->db->join('kelas', 'siswa.kelas_id = kelas.id', 'left');