Are there specific PHP functions or commands that need to be used to retrieve passwords from a database for comparison?

To retrieve passwords from a database for comparison in PHP, you typically need to use SQL queries to select the password associated with a specific username or email. Once you retrieve the password from the database, you can compare it with the user-inputted password using PHP functions like password_verify() for secure password hashing and verification. 

// Assume $username or $email is the user input
// Connect to the database
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Retrieve password from the database based on username or email
$sql = "SELECT password FROM users WHERE username = '$username' OR email = '$email'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        $hashed_password = $row["password"];
        
        // Compare retrieved password with user-inputted password
        if (password_verify($user_inputted_password, $hashed_password)) {
            // Passwords match
            echo "Password is correct";
        } else {
            // Passwords do not match
            echo "Password is incorrect";
        }
    }
} else {
    echo "0 results";
}

$conn->close();

Keywords

PHP database password retrieval comparison functions

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