Add a new field

How can I add a new field (Item Code) to the product page " items "  and Invoices.There after i need to search items using code or name in sales invoices. Alson need to raise delivery orders. Can I find help please ?

<p>How can I add a new field (Item Code) to the product page " items "  and Invoices.There after i need to search items using code or name in sales invoices. Alson need to raise delivery orders. Can I find help please ?</p>

You can use the SKU for that purpose.

<p>You can use the SKU for that purpose.</p>