排序数据错误代码点火器

Question

当我尝试将距离输入到 5 时，我在排序数据时遇到了一些问题，我遇到了这个错误：

 Unknown column 'dystans' in 'having clause'

 SELECT COUNT(*) AS `numrows` FROM `meet` JOIN `category` ON `category`.`id` = `meet`.`category_id` HAVING `dystans` <= '5' ORDER BY `when` ASC

Filename:    C:/xamppNew/htdocs/dzielimypasje/application/controllers/Meetings.php

Line Number: 177

我正在使用 codeigniter。第177行是这个

$data['count'] = $count = $this->db->count_all_results();

我的控制器：

$lat = $this->session->userdata('lat');
$lng = $this->session->userdata('lng');

        // To pagination
$this->load->library('pagination');
$limit = 10;
$offset = $this->uri->segment(4);

$this->db->start_cache();

    $this->db->select('*, meet.id, 
        (6731 * acos( cos( radians( '.$lat.')) * cos( radians( meet.lat)) *
   cos( radians( meet.lng) - radians( '.$lng.')) + sin( radians( '.$lat.')) *
   sin( radians( meet.lat)))) AS dystans');

         //data from search engine
    $level = $this->input->post('level');
    $cat = $this->input->post('category');
    $dystans = $this->input->post('dystans');
    $when = $this->input->post('when');

    if ($level) {
    $this->db->where('level', $level); 
    }
    if ($cat) {
    $this->db->where('category_id', $cat); 
    }
    if ($when) {
    $this->db->where('when <=', $when); 
    }
    if ($dystans) {
    $this->db->having('dystans <=', $dystans); 
    }
    $this->db->order_by('when', 'ASC');
    $this->db->from('meet');
    $this->db->join('category', 'category.id = meet.category_id');

$this->db->stop_cache();

        // count for pagination
    $data['count'] = $count = $this->db->count_all_results();

        // to pagination
    $this->db->limit($limit, $offset);

    $data['meetings'] = $this->db->get();
    $this->db->flush_cache();

    $config = some config for pagination ...

    $this->pagination->initialize($config); 

    $data['pagination'] = $this->pagination->create_links();


    $this->load->view( 'site/meetings/index' , $data );

查看：

   <select type="text" name="dystans" placeholder="distance">
           <option value="">Odległość</option>
           <option value="1">Do 1 km</option>
           <option value="2">Do 2km</option>
           <option value="5">Do 5km</option>
           <option value="10">Do 10km</option>
   </select>

知道如何解决这个问题吗？可能它有缓存但我不确定，我是新的。

Answer 1

好的。我深入研究并修复了我能找到的所有东西。我放弃了使用 query() 函数直接访问数据库的活动记录，因为......嗯......我从不喜欢活动记录，并且个人认为在管理工具中编写查询并将其复制到模型中要干净得多。这使您可以访问 mysql 的所有功能，而无需跳过障碍（更不用说，如果您将来使用不同的代码库，您已经有了查询并且不必重新挖掘所有活动记录代码）。

您在dystans 块中中断的主要原因是您试图在where 子句中使用动态生成的列。 where 子句只知道您已加入的表中存在的列。因此，要执行您需要的操作，您必须重新执行您的公式。

我还打破了这一点，以便所有过滤器都可以相互配合使用。用户现在可以在使用过滤器反斯坦时使用过滤器，并且将相应地构建查询。

我没有测试过这段代码，因为很明显我没有你的数据库，但这与我编写所有应用程序的方式相同。如果您有麻烦，请告诉我。

您还应该真正考虑将您的业务逻辑或至少数据库交互分解为一个 codeigniter 模型。控制器只能充当模型和视图之间的路由器。

The link to my post on codeigniter pagination

<?php

$lat = $this->session->userdata('lat');
$lng = $this->session->userdata('lng');

// To pagination
$this->load->library('pagination');
$limit = 10;
$offset = (isset($this->uri->segment(4)) && is_numeric($this->uri->segment(4))) ? $this->uri->segment(4) : 0;

$bindArray = array();

$query = "SELECT *,"
        . " (6731 * acos(cos( radians(?)) * cos( radians( meet.lat))"
        . " * cos( radians( meet.lng) - radians(?)) + sin( radians(?))"
        . " * sin( radians( meet.lat)))) AS dystans";

$bindArray[] = $lat;
$bindArray[] = $lng;
$bindArray[] = $lat;


$query .= " FROM meet JOIN category ON category.id = meet.category_id"
        . " WHERE TRUE = TRUE";

//data from search engine
$level = $this->input->post('level');
$cat = $this->input->post('category');
$dystans = $this->input->post('dystans');
$when = $this->input->post('when');

if($level){
    $query .= " AND meet.level = ?";
    $bindArray[] = $level;
}
if($cat){
    $query .= " AND meet.category_id = ?";
    $bindArray[] = $cat;
}
if($when){
    $query .= " AND meet.when <= ?";
    $bindArray[] = $when;
}
if($dystans){
    $query .= " AND (6731 * acos(cos( radians(?)) * cos( radians( meet.lat))"
            . " * cos( radians( meet.lng) - radians(?)) + sin( radians(?))"
            . " * sin( radians( meet.lat)))) <= ?";
    $bindArray[] = $dystans;
}

$query .= "LIMIT ?,?";
$bindArray[] = $offset;
$bindArray[] = $limit;

$query_result = $this->db->query($query, $bindArray);

$data['count'] = $query_result->num_rows();
$data['meetings'] = $query_result->result();

$config = 'YOUR PAGINATION CONFIGURATION';

$this->pagination->initialize($config); 

$data['pagination'] = $this->pagination->create_links();


$this->load->view( 'site/meetings/index' , $data );