How to use php to operate mysql to update query results

1. Using AJAX

In modern front-end development, the popularity of AJAX technology makes JavaScript and backend communication more convenient. Through AJAX, the data generated by the PHP page can be easily obtained and used to dynamically update the website.

AJAX gets data from PHP (generally JSON), and then uses DOM operations to update HTML elements to update the data. 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
    }
});

We send the data to be updated to the PHP page "update.php" as this example. Next, the PHP page processes the data, updates the database, and returns a result in JSON format. 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.

WebSocket makes it possible to update data in real time on either the server or the client without any delay. WebSocket's high update efficiency makes 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 a web development technology that allows the client to keep the HTTP connection open for a certain period of time. Open status. The server will send a response when there is data to update, otherwise it will keep the connection open.

Using long polling technology, PHP and MySQL query results can be updated in real time, similar to the effects of 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
        }
    });
}

We used two PHP scripts, one is update.php and the other is long-poll.php. On the initial request, update.php will return data and set the timeout for PHP to wait for background events. If there is data update, the data is returned to the client.

In the absence of data updates, long polling will return an empty response but will not close the HTTP connection. This way the client keeps the connection open but can maintain the current state of the response. Long-poll.php will send a response about the data update to the client, so that the client can get the updated data.

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