How to use PHP and CGI to implement website paging and sorting functions

How to use PHP and CGI to implement the paging and sorting functions of the website

Preface
Paging and sorting of the website are very common and important functions, especially for the display and processing of large amounts of data. In this article, we will use PHP and CGI (Common Gateway Interface) technology to implement the paging and sorting functions of the website, with corresponding code examples.

1. Implementation of the paging function
The paging function mainly obtains a specific range of data by querying the database, and displays the data according to the specified page number and display quantity per page. The following are the steps to implement the paging function:

1. Get the total amount of data
   Before executing the query, we need to know how many pieces of data there are in the database. The total amount of data can be obtained through the following code:

   $query = "SELECT COUNT(*) as total FROM table";
   $result = mysqli_query($conn, $query);
   $row = mysqli_fetch_assoc($result);
   $total = $row['total'];

2. Set the number of data displayed on each page and the total number of pages
   According to the user's needs, you can set the number of data displayed on each page, such as 10 or 20. Based on the total amount of data and the number displayed on each page, the total number of pages can be calculated:

   $per_page = 10; // 每页显示数量
   $total_pages = ceil($total / $per_page); // 总页数

3. Get the current page number
   Users can specify the current page number through URL parameters or other methods. The following code can obtain the current page number specified by the user:

   $current_page = isset($_GET['page']) ? $_GET['page'] : 1; // 当前页码，默认为第一页

4. Calculate offset
   According to the current page number and the number displayed on each page, the offset when querying data can be calculated:

   $offset = ($current_page - 1) * $per_page; // 偏移量

5. Execute query
   Finally, based on the calculated offset and the number of displays per page, execute the query and obtain the data within the specified range. The following code example demonstrates the query process:

   $query = "SELECT * FROM table LIMIT $offset, $per_page";
   $result = mysqli_query($conn, $query);
   while ($row = mysqli_fetch_assoc($result)) {
     // 处理数据
   }

6. Display paging links
   In order to allow users to browse and switch pages easily, we need to display paging links in the page. The following code example shows how to generate pagination links:

   for ($i = 1; $i <= $total_pages; $i++) {
     echo "<a href='?page=$i'>$i</a> ";
   }

The above are the steps and code examples for using PHP and CGI to implement website paging functionality. Next, we will introduce how to implement the sorting function of the website.

2. Implementation of sorting function
The sorting function is used to sort the displayed data. Users can choose to sort in ascending or descending order according to a certain field according to their own needs. The following are steps and code examples to implement the sorting function:

1. Get the sorting field and sorting method selected by the user
   Users can specify the sorting field and sorting method through URL parameters or other methods . The following code can obtain the sorting field and sorting method selected by the user:

   $sort_field = isset($_GET['sort_field']) ? $_GET['sort_field'] : 'id'; // 排序字段，默认为id
   $sort_order = isset($_GET['sort_order']) ? $_GET['sort_order'] : 'asc'; // 排序方式，默认为升序

2. Build a sorting SQL statement
   Construct the corresponding SQL statement based on the sorting field and sorting method selected by the user. The following code example shows how to construct a sorting SQL statement:

   $order_by = "ORDER BY $sort_field $sort_order";

3. Execute query
   Finally, based on the constructed sorting SQL statement, execute the query and obtain the sorted data. The following code example shows the query process:

   $query = "SELECT * FROM table $order_by";
   $result = mysqli_query($conn, $query);
   while ($row = mysqli_fetch_assoc($result)) {
     // 处理数据
   }

4. Display sorting link
   In order to allow users to easily switch the sorting method, we need to display the sorting link on the page. The following code example shows how to generate sorting links:

   echo "<a href='?sort_field=id&sort_order=asc'>按ID升序排序</a> ";
   echo "<a href='?sort_field=id&sort_order=desc'>按ID降序排序</a> ";

With the above steps and code examples, we can easily implement the sorting function of the website.

Conclusion
Through this article, we learned how to use PHP and CGI to implement the paging and sorting functions of the website, and attached the corresponding code examples. These features are very useful for handling the presentation and processing of large amounts of data, providing better user experience and results. Hope this article can be helpful to you!

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