Detailed tutorial on establishing a database connection using MySQLi in PHP

How to use MySQLi to establish a database connection in PHP: Include MySQLi extension (require_once) Create connection function (function connect_to_db) Call connection function ($conn = connect_to_db()) Execute query ($result = $conn->query( )) Close the connection ($conn->close())

Use MySQLi in PHP to establish a database connection

Introduction

MySQLi is an extension in PHP used to interact with the MySQL database. It provides a simple and efficient way to establish a database connection and execute queries. This article will provide a detailed guide on how to establish a database connection using MySQLi in PHP, including practical examples.

Prerequisites

Before continuing, make sure the following prerequisites are met:

• PHP Installation and Configuration
• MySQL Databases and Servers
• MySQLi extension enabled or installed

Step 1: Include the MySQLi extension

First, include the MySQLi extension to your In PHP script:

<?php
require_once 'path/to/mysqli_connect.php';
?>

Step 2: Create connection function

In order to reuse the connection code, create a function to establish the MySQLi connection:

<?php

function connect_to_db() {
    $hostname = 'localhost';
    $username = 'root';
    $password = '';
    $database = 'my_database';
    $conn = new mysqli($hostname, $username, $password, $database);
    if ($conn->connect_error) {
        die("连接失败: " . $conn->connect_error);
    }
    return $conn;
}
?>

Step 3: Call the connection function

In your script, obtain the MySQLi connection by calling the connect_to_db() function:

<?php

$conn = connect_to_db();
?>

Step 4: Execute the query

Now, you can use the connection object to execute MySQL queries:

<?php

$result = $conn->query("SELECT * FROM users");
if (!$result) {
    die("查询失败: " . $conn->error);
}

// 处理查询结果...
?>

Step 5: Close the connection

Finally, close at the end of the script MySQLi connection to release resources:

<?php

$conn->close();
?>

Practical case

The following is a simple example of how to use MySQLi to connect to a database and retrieve data:

<?php

$conn = connect_to_db();

$result = $conn->query("SELECT * FROM users");

while ($row = $result->fetch_assoc()) {
    echo $row['id'] . ' ' . $row['name'] . '<br>';
}

$conn->close();
?>

Conclusion

By following these steps, you can easily establish a database connection and execute MySQL queries using MySQLi in PHP. By reusing connection functions and releasing resources correctly, you can ensure a stable and efficient database connection.

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