Quick Answer

Fix database connection issues.

Understanding the Issue

This occurs when PHP cannot connect to MySQL due to incorrect credentials, host issues, or insufficient privileges.

The Problem

This code demonstrates the issue:

Php Error 
<?php
$conn = mysqli_connect("localhost", "wronguser", "wrongpass");

The Solution

Here's the corrected code:

Php Fixed 
<?php
// Verify credentials
$host = "localhost";
$user = "correct_user";
$pass = "secure_password";
$db   = "database_name";

// Connect with error handling
$conn = mysqli_connect($host, $user, $pass, $db);
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// PDO alternative with try-catch
try {
    $pdo = new PDO("mysql:host=$host;dbname=$db", $user, $pass);
} catch (PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}

Key Takeaways

Verify database credentials and connection parameters.