4) Create database package pointOfSal which contain the following

I. procedure to remove item from customer invoice removeInvoiceItem(invoiceNo, itemName) where this method will firstly call getItemNo(itemNAme) method which it will return item no if exists else it will return -1 if not exists . After that the procedure will call function

checkExistingInvoiceItem(invoiceNo,itemNo) which will return exists if this item was sell in this invoice or not exists if not was sell. After that the procedure will call getitemInvoiceQuantity(invoiceNo,itemNo) ,getitemInvoicepaidprice(invoiceNo,itemNo) for existingitem in this invoice , then this function it will return the quantity for this item was sell to customer in this invoicethen the procedure will increase the total_quantity for this item in items table ,then it will decrease the total price related to this invoice by this formula {total price =total price (quantity*price)}