如何将codeigniter活动记录放入if语句中

Question

$this->db->where('teacher_name_1 IS NOT NULL', NULL, FALSE); 
$this->db->where('course_id', $course_id); 
$this->db->update('tbl_course_choice', $teacher_name_2); 

$this->db->where('teacher_name_2 IS NOT NULL', NULL, FALSE); 
$this->db->where('course_id', $course_id); 
$this->db->update('tbl_course_choice', $teacher_name_3); 

$this->db->where('teacher_name_3 IS NOT NULL', NULL, FALSE); 
$this->db->where('course_id', $course_id); 
$this->db->update('tbl_course_choice', $teacher_name_4); 

$this->db->where('teacher_name_4 IS NOT NULL', NULL, FALSE); 
$this->db->where('course_id', $course_id); 
$this->db->update('tbl_course_choice', $teacher_name_5); 

$this->db->where('teacher_name_5 IS NOT NULL', NULL, FALSE); 
$this->db->where('course_id', $course_id); 
$this->db->update('tbl_course_choice', $teacher_name_6); 

如何将此代码放入if elseif语句中。我尝试了几种方法，但是失败了。

例子：

if ($this->db->where('teacher_name_1 IS NOT NULL', NULL, FALSE)) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_2); 
} 
elseif ($this->db->where('teacher_name_2 IS NOT NULL', NULL, FALSE)) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_3); 
} 
elseif ($this->db->where('teacher_name_3 IS NOT NULL', NULL, FALSE)) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_4); 
} 
elseif ($this->db->where('teacher_name_4 IS NOT NULL', NULL, FALSE)) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_5); 
} 
elseif ($this->db->where('teacher_name_5 IS NOT NULL', NULL, FALSE)) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_6); 
} 
else { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_1); 
} 

的哪些错误？请帮我弄清楚。谢谢后

编辑 我完全控制一些修改，但仍然没有工作..

$user_name = $this->the_user->username; 
$course_id = $this->input->post('course_id'); 
    $course_code = $this->input->post('course_code'); 
    $course_title = $this->input->post('course_title'); 
    $credit_hours = $this->input->post('credit_hours'); 
    $contact_hours = $this->input->post('contact_hours'); 
    $section = $this->input->post('section'); 
    $teacher = $this->input->post('teacher'); 

    $course_type = $this->input->post('course_typ'); 
    $pre_requisite = $this->input->post('pre_requisit'); 
    $year = $this->input->post('yea'); 
    $semester = $this->input->post('semeste'); 
    $teacher_name_1 = $user_name; 
    $offering_year = $this->input->post('offering_year'); 
    $offering_session = $this->input->post('offering_session'); 

    $ql = $this->db->select('course_id')->from('tbl_course_choice')->where('course_id',$course_id)->get(); 
    if($ql->num_rows() > 0) { 
     $teacher_name_1 = array(
     'teacher_name_1' => 'mehdi hasan 1' 
     ); 
     $teacher_name_2 = array(
     'teacher_name_2' => 'mehdi hasan 2' 
     ); 
     $teacher_name_3 = array(
     'teacher_name_3' => 'mehdi hasan three' 
     ); 
     $teacher_name_4 = array(
     'teacher_name_4' => 'mehdi hasan four' 
     ); 
     $teacher_name_5 = array(
     'teacher_name_5' => 'mehdi hasan 5' 
     ); 
     $teacher_name_6 = array(
     'teacher_name_6' => 'mehdi hasan 6' 
     ); 
    $this->db->where('teacher_name_1 != ', ''); 
$this->db->where('course_id', $course_id); 
$query_2 = $this->db->get('tbl_course_choice'); 
$teacher_2_count = $query_2->num_rows(); 

$this->db->where('teacher_name_2 != ', ''); 
$this->db->where('course_id', $course_id); 
$query_3 = $this->db->get('tbl_course_choice'); 
$teacher_3_count = $query_3->num_rows(); 

$this->db->where('teacher_name_3 != ', ''); 
$this->db->where('course_id', $course_id); 
$query_4 = $this->db->get('tbl_course_choice'); 
$teacher_4_count = $query_4->num_rows(); 

$this->db->where('teacher_name_4 != ', ''); 
$this->db->where('course_id', $course_id); 
$query_5 = $this->db->get('tbl_course_choice'); 
$teacher_5_count = $query_5->num_rows(); 

$this->db->where('teacher_name_5 != ', ''); 
$this->db->where('course_id', $course_id); 
$query_6 = $this->db->get('tbl_course_choice'); 
$teacher_6_count = $query_6->num_rows(); 

if ($teacher_2_count > 0) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_2); 
    } elseif ($teacher_3_count > 0) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_3); 
    } elseif ($teacher_4_count > 0) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_4); 
    } elseif ($teacher_5_count > 0) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_5); 
    } elseif ($teacher_6_count > 0) { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_6); 
    } else { 
    $this->db->where('course_id', $course_id); 
    $this->db->update('tbl_course_choice', $teacher_name_1); 
    } 
    } else { 
     $a = array(
      'course_id' => $course_id, 
      'course_code' => $course_code, 
      'course_title' => $course_title, 
      'course_type' => $course_type, 
      'credit_hours' => $credit_hours, 
      'contact_hours' => $contact_hours, 
      'section' => $section, 
      'teacher' => $teacher, 
      'pre_requisite' => $pre_requisite, 
      'year' => $year, 
      'semester' => $semester, 
      'offering_year' => $offering_year, 
      'offering_session' => $offering_session, 
      'teacher_name_1' => $teacher_name_1 
      ); 
     $this->db->insert('tbl_course_choice', $a); 
    } 

Answer 1

使用此代码

$this->db->where('teacher_name_2 != ', ''); 
    $this->db->where('course_id', $course_id); 
    $query_2 = $this->db->get('tbl_course_choice'); 
    $teacher_2_count = $query_2->num_rows(); 


    $this->db->where('teacher_name_3 != ', ''); 
    $this->db->where('course_id', $course_id); 
    $query_3 = $this->db->get('tbl_course_choice'); 
    $teacher_3_count = $query_3->num_rows(); 



    $this->db->where('teacher_name_4 != ', ''); 
    $this->db->where('course_id', $course_id); 
    $query_4 = $this->db->get('tbl_course_choice'); 
    $teacher_4_count = $query_4->num_rows(); 



    $this->db->where('teacher_name_5 != ', ''); 
    $this->db->where('course_id', $course_id); 
    $query_5 = $this->db->get('tbl_course_choice'); 
    $teacher_5_count = $query_5->num_rows(); 


    $this->db->where('teacher_name_6 != ', ''); 
    $this->db->where('course_id', $course_id); 
    $query_6 = $this->db->get('tbl_course_choice'); 
    $teacher_6_count = $query_6->num_rows(); 






if ($teacher_2_count > 0) { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_2); 
     } elseif ($teacher_3_count > 0) { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_3); 
     } elseif ($teacher_4_count > 0) { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_4); 
     } elseif ($teacher_5_count > 0) { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_5); 
     } elseif ($teacher_6_count > 0) { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_6); 
     } else { 
     $this->db->where('course_id', $course_id); 
     $this->db->update('tbl_course_choice', $teacher_name_1); 
     } 
}