Codeigniter：查询返回 NULL 值

Question

您好，我正在尝试检查我的查询是否成功，但它正在返回 NULL 值的索引，这使得查询看起来是成功的。如何检查示例查询中的查询是否成功，因为我认为它不应该返回 NULL 索引。

型号

 public function classmanage_classinfo($section_id) {
            $query = $this->db->select('students.user_id, students.studentnumber, 
                students.lastname, students.firstname, students.middlename, students.level, students.year')->from('sections')
            ->join('student_section', 'student_section.section_id = sections.section_id', 'left')
            ->join('students', 'students.user_id = student_section.student_id', 'left')
            ->where('sections.section_id', $section_id)
            ->get();

    if ($query->num_rows() > 0) {
        return $query->result();
    } else {
        return false;
    }
 }

控制器

$data['class_info'] = $this->staff_model->classmanage_classinfo($section_id);

查看

<p><?php var_dump($class_info) ?></p>

根据我的 var_dump，即使索引为空，数组也算作一行？为什么会这样。我如何确保如果查询不成功，它会在我的 if 语句中触发 false。如果有办法改进或解决这个逻辑，那将是最受欢迎的。谢谢。

编辑：

完整的控制器

$data['class_info'] = $this->staff_model->classmanage_classinfo($section_id);//determinant if query is null is in the model
            $data['section_info'] = $this->staff_model->classmanage_sectioninfo($section_id);

完整模型

public function classmanage_classinfo($section_id) {
        $query = $this->db->select('students.user_id, students.studentnumber, 
            students.lastname, students.firstname, students.middlename, students.level, students.year')->from('sections')
        ->join('student_section', 'student_section.section_id = sections.section_id', 'left')
        ->join('students', 'students.user_id = student_section.student_id', 'left')
        ->where('sections.section_id', $section_id)
        ->get();

        if ($query->num_rows() > 0) {
            return $query->result();
        } else {
            return false;
        }
    }

    public function classmanage_sectioninfo($section_id) {
        //section_name
        $query = $this->db->select('section_name')->where('section_id', $section_id)->get('sections');

        return $query->row();

    }

Answer 1

我假设您的查询返回多行而不是单行。

 $query = $this->db->select('students.user_id, students.studentnumber, 
            students.lastname, students.firstname, students.middlename, students.level, students.year')->from('sections')
        ->join('student_section', 'student_section.section_id = sections.section_id', 'left')
        ->join('students', 'students.user_id = student_section.student_id', 'left')
        ->where('sections.section_id', $section_id)
        ->get()->result();



if (!empty($query)) {
    return $query->result();
} else {
    return false;
}