This tutorial will teach you how to do auto generate  Invoice No using Php Mysql step by step i attached full source code below.i explained more clearly in the video tutorial attached below. <?php $servername = "localhost"; $username = "root"; $password = ""; $dbname = "minventory"; $conn = mysqli_connect($servername,$username,$password,$dbname); ?> <?php $query = "SELECT invoiceid FROM sales ORDER BY invoiceid …