How to use php to operate mysql to update query results

PHP and MySQL are two very popular programming languages ​​and database management systems that are widely used in the modern IT field. When a website or application is developed, PHP and MySQL are widely used to update and query data.

When a PHP page queries data from a MySQL database, especially when the data is modified, the query results often need to be updated in real time. This article will introduce how to use php to operate mysql to update query results.

1. Using AJAX

In modern front-end development, AJAX technology is widely used to implement JavaScript and backend communication. AJAX provides an easy way to obtain data generated by PHP pages and use it to dynamically update the website.

When data needs to be updated, AJAX gets the data (usually JSON) from PHP and then updates the HTML elements through DOM operations. This allows us to update the data in real time without having to refresh the entire web page.

The following is a simple example:

$.ajax({
    url: 'update.php',
    method: 'post',
    data: {
        // 发送到update.php的数据
    },
    success: function(data) {
        // 成功获取返回的数据
        // 使用DOM操作更新HTML元素
    }
});

In this example, we send the data to be updated to a PHP page named "update.php". The PHP page will then process the data, update the database and return a JSON-formatted result. Finally, through the success callback function, we achieve real-time update of data.

2. Using WebSocket

WebSocket is a two-way communication protocol that allows a persistent connection to be established between client JavaScript and back-end PHP. In this way, we can get data in real time like AJAX.

Using WebSocket, we can update data in real time anywhere on the server or client without any delay. Updating data using WebSocket is extremely efficient, making it widely used in games, group chats, and other real-time applications.

The following is a simple example:

var conn = new WebSocket('ws://localhost:8080');
conn.onmessage = function(event) {
    // 实时更新数据
};

In this example, we connect to a server named "ws://localhost:8080" through WebSocket. When data is updated, we will immediately receive an event callback and update the data.

3. Use Long Polling

Long polling is another web development technology that allows the client to maintain an HTTP connection for a period of time Open status. The server will send a response when there is data to update, otherwise it will keep the connection open.

Long polling technology allows us to update PHP and MySQL query results in real time like AJAX and WebSocket. Compared to WebSocket, long polling allows us to achieve real-time data updates in all browsers, not just those supported by WebSockets.

The following is a simple example:

$.ajax({
    url: 'update.php',
    method: 'post',
    data: {
        // 发送到update.php的数据
    },
    success: function(data) {
        // 成功获取返回的数据
        // 使用DOM操作更新HTML元素
        setTimeout(longPoll, 0); // 函数递归
    },
    error: function() {
        setTimeout(longPoll, 0); // 函数递归
    }
});

function longPoll() {
    $.ajax({
        url: 'long-poll.php',
        method: 'post',
        data: {
            // 发送到long-poll.php的数据
        },
        success: function(data) {
            // 成功获取返回的数据
            // 更新HTML元素
            setTimeout(longPoll, 0); // 函数递归
        },
        error: function() {
            setTimeout(longPoll, 0); // 函数递归
        }
    });
}

In this example, we use two PHP scripts: update.php and long-poll.php. update.php returns data on the initial request and sets the timeout for PHP to wait for background events. If there is data update, the data is returned to the client.

If no data is updated, long polling returns an empty response but does not close the HTTP connection. This way the client keeps the connection open but can maintain the current state of the response. When the data is updated, long-poll.php will send a response and the client will update the data.

Conclusion

There are many ways to update PHP and MySQL query results, and we have introduced some common technologies: AJAX, WebSocket, and long polling. Choose different technologies according to your needs to better achieve real-time data updates.

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