Difference between current date and past date using MySQL

Below is the function to get the time difference between Current date and the past date using MySQL. Mainly it can be used where we want to display the time gap between the registration of the user.

function getTimeDifference($created_since)

{

            $datediffquery = mysql_query  ("SELECT CASE WHEN TIMESTAMPDIFF(YEAR ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(YEAR ,'".$created_since."', NOW()), ' years ago')

                                                WHEN TIMESTAMPDIFF(YEAR ,'". $created_since."', NOW()) > 0 THEN CONCAT(TIMESTAMPDIFF(YEAR ,'". $created_since ."', NOW()), ' year ago')

                                                WHEN TIMESTAMPDIFF(MONTH ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(MONTH ,'".$created_since."', NOW()), ' months ago')

                                                WHEN TIMESTAMPDIFF(MONTH ,'".$created_since."', NOW()) > 0 THEN CONCAT(TIMESTAMPDIFF(MONTH ,'".$created_since."', NOW()), ' month ago')

                                                WHEN TIMESTAMPDIFF(DAY ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(DAY ,'".$created_since."', NOW()), ' days ago')

                                                WHEN TIMESTAMPDIFF(DAY ,'".$created_since."', NOW()) > 0 THEN CONCAT(TIMESTAMPDIFF(DAY ,'".$created_since."', NOW()), ' day ago')

                                                WHEN TIMESTAMPDIFF(HOUR ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(HOUR ,'".$created_since."', NOW()), ' hours ago')

                                                WHEN TIMESTAMPDIFF(HOUR ,'".$created_since."', NOW()) > 0 THEN CONCAT(TIMESTAMPDIFF(HOUR ,'".$created_since."', NOW()), ' hour ago')

                                                WHEN TIMESTAMPDIFF(MINUTE ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(MINUTE ,'".$created_since."', NOW()), ' minutes ago')

                                                WHEN TIMESTAMPDIFF(MINUTE ,'".$created_since."', NOW()) > 0 THEN CONCAT(TIMESTAMPDIFF(MINUTE ,'".$created_since."', NOW()), ' minute ago')

                                                WHEN TIMESTAMPDIFF(SECOND ,'".$created_since."', NOW()) > 1 THEN CONCAT(TIMESTAMPDIFF(SECOND ,'".$created_since."', NOW()), ' seconds ago')

                                            END

                                        AS total_days");

            

            $row = mysql_fetch_assoc($datediffquery);

            

            return $row['total_days'];

        }