Why is it considered a best practice to have a unique ID for each user in a database instead of using a password for identification in PHP?

It is considered a best practice to have a unique ID for each user in a database instead of using a password for identification in PHP because IDs are typically unique and do not change, while passwords can be changed by the user. Storing and using a unique ID for identification purposes is more secure and efficient than using passwords, which are meant for authentication. Additionally, using IDs simplifies database queries and ensures consistency in user identification.

// Example of using unique ID for user identification in PHP
$user_id = 123; // Unique ID for user
// Query database using the user ID
$query = "SELECT * FROM users WHERE id = $user_id";
// Execute query and retrieve user data
$result = mysqli_query($connection, $query);
$user = mysqli_fetch_assoc($result);

// Now you can use the $user array to access user information
echo "User ID: " . $user['id'];
echo "Username: " . $user['username'];
echo "Email: " . $user['email'];