使用 PHP OOP 概念连接到 MySQL 数据库 [英] Connect to MySQL database using PHP OOP concept

问题描述

我正在编写一个类和一些函数来连接到数据库并从表中检索信息.我浏览了以前标题相似的帖子，但其中大多数是使用 mysql 函数编写的，而我正在使用 mysqli 函数.

I'm writing a class and handful of functions to connect to the database and retrieve the information from the tables. I went through previous posts having similar titles, but most of them have written using mysql functions and I am using mysqli functions.

我希望有人能够完成这个简单的脚本，并让我知道我在哪里犯了错误.

I want somebody who can go through this simple script and let me know where I am making my mistake.

这是我的class.connect.php:

<?php

    class mySQL{
        var $host;
        var $username;
        var $password;
        var $database;
        public $dbc;

        public function connect($set_host, $set_username, $set_password, $set_database)
        {
            $this->host = $set_host;
            $this->username = $set_username;
            $this->password = $set_password;
            $this->database = $set_database;

            $this->dbc = mysqli_connect($this->host, $this->username, $this->password,           $this->database) or die('Error connecting to DB');        
        }

        public function query($sql)
        {
            return mysqli_query($this->dbc, $sql) or die('Error querying the Database');
        }

        public function fetch($sql)
        {        
            $array = mysqli_fetch_array($this->query($sql));          
            return $array;
        }

        public function close()
        {
            return mysqli_close($this->dbc);
        }
    }
    ?>

这是我的index.php:

<?php
        require_once ("class.connect.php");

        $connection = new mySQL();

        $connection->connect('localhost', 'myDB', 'joker', 'names_list');
        $myquery = "SELECT * FROM list";
        $query = $connection->query($myquery);        

        while($array = $connection->fetch($query))
        {
            echo $array['first_name'] . '<br />';
            echo $array['last_name'] . '<br />';                
        }

        $connection->close();
?>

我收到错误消息，说查询数据库时出错.

推荐答案

问题在于:

    public function fetch($sql)
    {        
        $array = mysqli_fetch_array($this->query($sql));          
        return $array;
    }

或者这个:

 while($array = $connection->fetch($query))

因为您正在使用查询的结果再次查询.基本上，您正在做:

Because you are using the result from the query to query again. Basically, you are doing:

$r = mysqli_query($this->dbc, $sql);
$array = mysqli_fetch_array(mysqli_query($this->dbc, $r));

并且您收到错误消息，因为 $r 不是查询字符串.当它转换为字符串时，它是一个1"(来自您的其他评论).

And you are getting an error, because $r is not a query string. When it's converted to a string, it's a "1" (from your other comment).

尝试将函数更改为(更改变量名称以便您可以看到差异):

Try changing the function to (changed name of variable so you can see the difference):

    public function fetch($result)
    {        
        return mysqli_fetch_array($result);
    }

或者直接调用函数.

这篇关于使用 PHP OOP 概念连接到 MySQL 数据库的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！