Connecting to MySQL Database with PHP

Connecting PHP with a MySQL database is a fundamental step in developing dynamic web applications. PHP provides the mysqli_connect() function to establish a connection to a MySQL database.

🔧 Preparation

Before creating the connection, ensure that:

You have a local server like XAMPP, Laragon, or WAMP.
The database is already created (e.g., a database named siswa).
PHP and MySQL are running on your local server.

💡 Basic Connection Structure

Here’s an example of a basic database connection using mysqli:

<?php

$host = "localhost";         // Hostname (usually 'localhost')
$username = "root";          // MySQL username (default: root in XAMPP)
$password = "";              // MySQL password (usually empty in XAMPP)
$db_name = "siswa";          // Name of the database

$connection = mysqli_connect($host, $username, $password, $db_name);

if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
} else {
    echo "Database connection successful";
}

?>

🔍 Code Explanation

Code Segment	Explanation
`$host = "localhost";`	Database server. Usually “localhost” on a local server.
`$username = "root";`	MySQL access username. Default in XAMPP is “root”.
`$password = "";`	User password. Usually empty on local servers.
`$db_name = "siswa";`	The name of the database to connect. Ensure it has been created.
`mysqli_connect(...)`	PHP function to establish a connection to MySQL.
`!$connection`	Checks whether the connection was successful.
`mysqli_connect_error()`	Displays the error message if the connection fails.
`echo "Database connection successful";`	Displays message if connection is successful.

🛠 Additional Tips

Save your connection file as koneksi.php, then include or require it in other PHP pages:

include 'koneksi.php';
// or
require 'koneksi.php';

Use require_once to ensure the file is included only once:

require_once 'koneksi.php';

For real-world applications:
- Do not display error messages directly in production.
- Use a .env file or hidden configuration for credentials.
- Use PDO or mysqli with prepared statements to prevent SQL Injection.

❗ Common Errors

Issue	Solution
Connection failed	Double-check host, username, password, and database name.
No success message shown	Ensure Apache and MySQL servers are running.
`mysqli_connect()` undefined	PHP lacks the mysqli extension. Enable it in php.ini if needed.

📚 Conclusion

Connecting to a database is the foundation of almost every dynamic web application. Understanding this structure is essential to build applications that interact with MySQL data. Once connected, you can run queries to display, store, or manipulate your data.

🚀 Next Steps

After mastering database connection, explore the following topics:

Executing SQL queries with PHP
Displaying data from the database
Input via HTML forms
Security (validation & data sanitation)