How to Connect to a PHP Database

Download: How to Connect to a PHP Database.mp4

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How to Connect to a PHP Database (MySQL)

PHP connects to databases mainly using MySQLi or PDO.
👉 PDO is recommended because it’s more secure and supports multiple databases.

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1. Prerequisites

Before connecting, make sure you have:

• A running web server (XAMPP, WAMP, MAMP, or Linux LAMP)

• PHP installed

• MySQL/MariaDB database

• Database credentials:

  • Host (usually localhost)

  • Database name

  • Username

  • Password

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2. Database Connection Using PDO (Recommended)

Basic PDO Connection Code

<?php
$host = "localhost";
$dbname = "my_database";
$username = "db_user";
$password = "db_password";

try {
    $conn = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Database connected successfully";
} catch (PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}
?>

✅ Why Use PDO?

• Prevents SQL Injection

• Supports prepared statements

• Works with multiple database types

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3. Database Connection Using MySQLi (Alternative)

MySQLi Procedural

<?php
$conn = mysqli_connect("localhost", "db_user", "db_password", "my_database");

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

MySQLi Object-Oriented

<?php
$conn = new mysqli("localhost", "db_user", "db_password", "my_database");

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
?>

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4. Best Practice: Separate Connection File

Create config.php

<?php
$host = "localhost";
$dbname = "my_database";
$username = "db_user";
$password = "db_password";

try {
    $conn = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("DB Error: " . $e->getMessage());
}
?>

Include it in other files:

<?php
require "config.php";
?>

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5. Test the Connection

• Save the file as test.php

• Open in browser:

http://localhost/test.php

If successful, you’ll see:

Database connected successfully

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6. Common Connection Errors & Fixes

Error	Solution
Access denied	Check username/password
Database not found	Verify DB name
Connection refused	Ensure MySQL is running
Charset issues	Use charset=utf8

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7. Security Tips 🚨

• ❌ Never hardcode credentials in public files

• ✅ Use .env files for production

• ✅ Always use prepared statements

• ❌ Don’t display DB errors in production

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Conclusion

Connecting PHP to a database is simple once you understand:

• Use PDO for security and flexibility

• Separate configuration files

• Handle errors properly

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