如何在 PHP 类中使用mysqli_query - How can I use mysqli_query inside PHP class?

How can I use mysqli_query inside PHP class?

本文关键字：mysqli query PHP | 更新日期: 2023-09-27

如何在类中使用$connect变量User而无需将$connect作为参数发送或在用户类中定义global $connect？

我只想创建一个连接是

$connect = mysqli_connect('localhost', 'root', '1234', 'mydatabase');

错误

警告：mysqli_query（）期望参数 1 是 mysqli，null 在第 9 行的 D：''xampp''htdocs''mateocode''index.php 中给出

示例代码

<?php
    class User {    
        public $id;
        public $username;
        function __construct($user_id)
        {   
        $sql = "select id, username from user where id = '$user_id' limit 1";
        $result = mysqli_query($connect, $sql);    
        if(!$result) return false;
        if(mysqli_num_rows($result)>0){
            $data = mysqli_fetch_assoc($result);
            $this->id = $data['id'];
            $this->username = $data['username'];
        }else{ 
            return false; 
        }   
    }
}
$connect = mysqli_connect('localhost', 'root', '1234', 'mydatabase');
if($objUser = new User(1))
    echo $objUser->username;
else 
    echo 'There was an error or user not found!';

尝试使用 -

<?php
    class User {    
        public $id;
        public $username;
        function __construct($user_id, $connect)
        {   
        $sql = "select id, username from user where id = '$user_id' limit 1";
        $result = mysqli_query($connect, $sql);    
        if(!$result) return false;
        if(mysqli_num_rows($result)>0){
            $data = mysqli_fetch_assoc($result);
            $this->id = $data['id'];
            $this->username = $data['username'];
        }else{ 
            return false; 
        }   
    }
}
$connect = mysqli_connect('localhost', 'root', '1234', 'mydatabase');
if($objUser = new User(1, $connect))
    echo $objUser->username;
else 
    echo 'There was an error or user not found!';