遇到 PHP 错误 严重性：通知消息：未定义变量：id 文件名：models/singlequery_model.php 行号：4 [重复]

Question

A PHP Error was encountered

Severity: Notice

Message: Undefined variable: id

Filename: models/singlequery_model.php

Line Number: 4

A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

SELECT * FROM 患者 WHERE id =

文件名：C:\xampp\htdocs\login\system\database\DB_driver.php

行号：330

这是查询单个结果的正确方法吗？

    <?php
class Singlequery_model extends CI_Model{
    function get_query(){
        $query = $this->db->query("SELECT * FROM patient WHERE id  = $id");

        if($query->num_rows() > 0 ){
            foreach ($query->result() as $row){
                $data[] = $row;
            }
            return $data;
        }
    }
}

下面是我的控制器

    <?php 
class Site extends CI_Controller{
    function __construct(){
      parent::__construct();
      $this->is_logged_in();
      $this->load->model('site_model');

    }
    function delete(){
      $this->site_model->delete_row();
      redirect('site/members_area');
    }

    function view(){

        $this->load->model('singlequery_model');

        $data['records'] = $this->singlequery_model->get_query();
        $this->load->view('patient_update', $data);

    }

}

Answer 1

$query = $this->db->query("SELECT * FROM patient WHERE id  = $id");

$id 没有在你的类中定义

为此，请确保使用$id 调用该函数：

$data['records'] = $this->singlequery_model->get_query($id);

我无法知道您的$id 来自哪里，所以您只能自己管理。