PHP implements a program to automatically delete useless images

With the rapid development of the Internet, more and more websites use pictures. Pictures play an irreplaceable role in websites. They can present website content more intuitively, attract users' attention, and improve the quality of the website. and image. However, pictures are a resource that consumes server space and bandwidth. When pictures are uploaded to the server, if they are not processed, they will continue to occupy server space, resulting in server performance degradation, and a large number of useless pictures will degrade the website. Speed ​​and user experience affect website SEO optimization. Therefore, it becomes important to automatically delete useless images.

PHP is an open source scripting language suitable for web development and can be used to write simple scripts or complex applications. Useless images can be easily and automatically deleted through PHP's file processing functions. The following will introduce in detail how to use PHP to write a program that automatically deletes useless images.

1. What are useless pictures

Useless pictures refer to pictures that are no longer used or are no longer displayed on the page. These pictures are uploaded to the server, but they increase the server's space load and overhead. If these pictures are not cleaned up in time, the server will continue to accumulate these discarded pictures, which will eventually lead to a decrease in server performance. Therefore, automatically deleting useless images is an essential program for website optimization.

2. How to find useless pictures

In the process of website development, we can use programs to find useless pictures. Automatically processing images can greatly reduce the workload of manually deleting images, and can also ensure the maintainability of the program. The following are the steps to use PHP to find useless pictures:

1. Find the data about the picture

First, we need to find the data about the picture from the website database. By querying all image link URLs in the database and the number of times the link is called, you can determine whether these images are useful. For important pictures, we can choose not to delete them automatically, but for some pictures that are no longer used and are rarely called, we can share them on the cloud storage platform to reduce the burden on the server.

2. Find useless pictures in the website

Use PHP to write a program to automate the process to find useless pictures in the website. The specific steps are as follows:

(1) Traverse all the pictures in the website and store the URL addresses of the pictures in the array.

(2) Loop through the array and query whether the image is referenced in the database. If not, delete the image from the website server space.

3. Specific implementation of PHP automatically deleting pictures

The following code segment uses PHP code to automatically delete useless pictures on the website:

<?php
//数据库连接
$link=mysql_connect("localhost","dbuser","dbpassword");
mysql_select_db("dbname",$link);

//从数据库中获取图片名及使用次数
$result=mysql_query("select pic_url,count(*) as count from pic_table group by pic_url");
while($row=mysql_fetch_array($result)){
    $pic_url=$row[&#39;pic_url&#39;];
    $count=$row[&#39;count&#39;];

    //检查文件是否存在
    if(file_exists($pic_url)){
        if($count<=0){
            //删除图片
            unlink($pic_url);
        }
    }
}

//关闭数据库连接
mysql_close($link);
?>

The above code is mainly through PHP The file processing function unlink() realizes automatic deletion of useless pictures. Among them, the URL address of the picture and the number of calls are first obtained through database query. After the picture URL is stored in the array, the array is then looped to check whether the picture exists. If it exists and the number of calls is less than or equal to 0, the picture is deleted. . Finally close the database connection.

IV. Summary

This article introduces the method of using PHP to automatically delete useless images. Through this method, website administrators can easily manage and maintain website images, clean up server space consumption and Bandwidth of useless images, reducing server burden, improving website performance and user experience, while complying with standardized website optimization processes. PHP has rich file processing functions. Other commonly used functions include copy(), rename(), mkdir(), rmdir(), etc. Developers can also choose to use them according to actual needs.

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