PHPRUNNER AUTO NUMBER

https://xlinesoft.com/blog/2019/02/07/using-invoice-template-as-a-checkout-solution/

1. rs = CustomQuery("select invnumber from invoice_number");  
2. $data = db_fetch_array($rs);  
3. $values['invoice_number'] = "INV-X".str_pad($data["invnumber"]+1, 7, "0",STR_PAD_LEFT);  
4. CustomQuery("update invoice_number set invnumber=invnumber+1");