我如何获得仅活跃的学生总数

Question

我有两个 table 存储学生数据 - students table 和 student_sessiontable

学生table结构

CREATE TABLE IF NOT EXISTS `students` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `parent_id` int(11) NOT NULL,
  `admission_no` varchar(100) DEFAULT NULL,
  `roll_no` varchar(100) DEFAULT NULL,
  `admission_date` date DEFAULT NULL,
  `firstname` varchar(100) DEFAULT NULL,
  `lastname` varchar(100) DEFAULT NULL,
  `rte` varchar(20) DEFAULT NULL,
  `image` varchar(100) DEFAULT NULL,
  `mobileno` varchar(100) DEFAULT NULL,
  `email` varchar(100) DEFAULT NULL,
  `is_active` varchar(255) DEFAULT 'yes',
  `disable_at` date NOT NULL,
  `created_at` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(),
  `updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

student_session table 结构

CREATE TABLE IF NOT EXISTS `student_session` (
  `id` int(11) NOT NULL,
  `session_id` int(11) DEFAULT NULL,
  `student_id` int(11) DEFAULT NULL,
  `class_id` int(11) DEFAULT NULL,
  `section_id` int(11) DEFAULT NULL,
  `route_id` int(11) NOT NULL,
  `hostel_room_id` int(11) NOT NULL,
  `vehroute_id` int(10) DEFAULT NULL,
  `transport_fees` float(10,2) NOT NULL DEFAULT 0.00,
  `fees_discount` float(10,2) NOT NULL DEFAULT 0.00,
  `is_active` varchar(255) DEFAULT 'no',
  `created_at` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(),
  `updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

现在，我已经能够使用此查询

获得 class 中的学生总数

 public function Gettotalstudents($session_id, $section_id, $class_id) 
    {
        $this->db->select('student_id');
        $this->db->where('session_id', $session_id);
        $this->db->where('section_id', $section_id);
        $this->db->where('class_id', $class_id);
        return $this->db->count_all_results('student_session');
    }

但是，也有一些学生因不交学费而致残或永久离开学校。问题是因为这些学生只是被禁用而没有被删除，查询仍然将他们计入活跃学生。

现在，我想把残疾学生排除在外。

注意 - 在学生table结构中，'is_active' 行存储学生是活动还是禁用的数据。 'yes'表示一个学生处于活动状态，'no'表示一个学生已被禁用。

我该怎么做？

Answer 1

您应该将 is_active 字段更改为布尔值。

加入学生 table 与 student_session.student_id = students.student_id，并按 is_active 筛选student_session

中的字段

Try this for active students in table students

public function Gettotalstudents($session_id, $section_id, $class_id) 
{
    $this->db->select('student_session.student_id');
    $this->db->from("student_session,students"); //session table and student table
    $this->db->where('student_session.student_id', 'student_id.student_id'); //join tables
    $this->db->where('student_session.session_id', $session_id);
    $this->db->where('student_session.section_id', $section_id);
    $this->db->where('student_session.class_id', $class_id);
    $this->db->where('student_id.is_active', 'yes'); //only active
    return $this->db->count_all_results(); // count active
}

Try this for active students in table student_session

 public function Gettotalstudents($session_id, $section_id, $class_id) 
{
    $this->db->select('student_id');
    $this->db->where('session_id', $session_id);
    $this->db->where('section_id', $section_id);
    $this->db->where('class_id', $class_id);
    $this->db->where('is_active', 'yes');
    return $this->db->count_all_results('student_session');
}

Answer 2

或者更简洁一点，您可以将 mysql COUNT() 函数与 AS:

一起使用

public function Gettotalstudents($session_id, $section_id, $class_id) 
    {
        $this->db->select('COUNT(ss.student_id) as total');
        $this->db->from('student_session ss');
        $this->db->join('students st', 'st.id = ss.student_id');
        $this->db->where(array('st.is_active'=> 'yes','ss.session_id' => $session_id, 'ss.section_id' => $section_id, 'ss.class_id' => $class_id));
        return $this->db->get()->row()->total;
    }

我如何获得仅活跃的学生总数

How do I get the total number of students who are only active

php

mysql

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