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How to read database in html

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Mar 26, 2024 pm 02:46 PM

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HTML itself does not have the ability to directly read the database, but needs to be implemented in combination with a back-end programming language and a database query language. The backend code is responsible for interacting with the database, reading data from the database, and embedding the data into HTML pages. This process typically involves setting up a database, writing backend code, embedding the backend code into HTML, configuring the server, and accessing web pages. In addition, front-end JavaScript can also read database data by interacting with the back-end API.

How to read database in html

#HTML itself does not have the ability to directly read the database. HTML is a markup language used to create web pages. It is mainly responsible for describing the structure and content of web pages and does not involve interaction with databases. To read the data in the database and present it on the HTML page, you usually need to use back-end programming languages (such as PHP, Python, Java, etc.) or front-end JavaScript technology, combined with database query languages (such as SQL).

The following is a simplified process describing how to use a back-end programming language and a database query language to read the database and embed the data into an HTML page:

1. Set up the database

First, you need to set up a database on the server to store and manage data. Popular database systems include MySQL, PostgreSQL, MongoDB, etc. You need to install database software and create a database and corresponding tables to store your data.

2. Write the back-end code

The back-end code will be responsible for handling the interaction with the database. You can write code using back-end technologies such as PHP, Python's Flask or Django framework, and Java's Spring framework. Here is a simple example using PHP and MySQL:

PHP Sample Code

<?php  
// 数据库连接信息  
$servername = "localhost";  
$username = "username";  
$password = "password";  
$dbname = "myDB";  
  
// 创建连接  
$conn = new mysqli($servername, $username, $password, $dbname);  
  
// 检测连接  
if ($conn->connect_error) {  
    die("连接失败: " . $conn->connect_error);  
}  
  
// 执行SQL查询  
$sql = "SELECT id, name FROM users";  
$result = $conn->query($sql);  
  
if ($result->num_rows > 0) {  
    // 输出数据  
    while($row = $result->fetch_assoc()) {  
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";  
    }  
} else {  
    echo "0 结果";  
}  
$conn->close();  
?>

3. Embed the backend code into HTML

You can The backend code is embedded directly into the HTML file, or an HTML file is generated using the backend code. If you choose to embed directly, you can use PHP's tag to include the PHP code. If you choose to generate an HTML file, the backend code can create an HTML string containing the query results and then write the string to a file or return it to the client as an HTTP response.

Embed PHP code into HTML

<!DOCTYPE html>  
<html>  
<head>  
    <title>读取数据库示例</title>  
</head>  
<body>  
    <h1 id="用户列表">用户列表</h1>  
    <ul>  
        <?php  
        // 这里可以包含上面提到的PHP代码片段  
        // ...  
        ?>  
    </ul>  
</body>  
</html>

4. Configure server

Your HTML files and back-end code need to be deployed on a web server, Such as Apache, Nginx or IIS. The server needs to be configured to be able to parse PHP (or other backend language) and connect to the database. This usually involves installing the appropriate language interpreter (such as the PHP interpreter) and database extension (such as the MySQL extension for PHP).

5. Access the webpage

Once your server is configured correctly, you can access your HTML pages through the browser. The browser will send a request to the server, the server will execute the back-end code, read the data from the database, and then return the HTML page containing the data to the browser.

Use front-end JavaScript to interact with the back-end API

In addition to generating HTML pages directly on the server side, you can also use front-end JavaScript to interact with the back-end API. The back-end API can expose one or more endpoints, and the front-end JavaScript calls these endpoints by sending HTTP requests (such as GET, POST, etc.) to obtain data in the database. This usually involves using technologies such as AJAX (Asynchronous JavaScript and XML) or the Fetch API.

Notes

1. Security: Security is crucial when interacting with the database. Make sure your backend code is protected against attacks such as SQL injection, and use prepared statements or an ORM (object-relational mapping) library to avoid splicing user input directly into SQL queries.

2. Performance: Large or complex database queries may affect website performance. Optimizing queries, using indexes, caching results, etc. are all effective ways to improve performance.

3. Error handling: When writing code that interacts with the database, ensure that possible errors, such as connection failures, query errors, etc., are properly handled, and provide meaningful feedback to users.

To summarize, reading a database and embedding its content into an HTML page is a complex process involving back-end programming, database querying, and web server configuration. By understanding these steps and best practices, you can effectively implement interactions between databases and HTML pages.

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