Hello,
For videos, this seems to be the site most refer to → TheFrugalComputerGuy.
You question does present some issues. First thought is a missing table - Customer, the main character. A customer can have multiple orders and an order can have multiple items. The Order is linked to the customer & the order items are linked to the order. Your 'Items" table (depending upon size and complexity) is simply used for items in a list box in the ordered items section.
Calculations (or totals) are typically not part of capturing data. This can be done later with SQL. If absolutely necessary and instant results are required, special macro(s) need to be written for this purpose. If only needed once the data has been completed, then SQL can work. Also certain databases (Firebird for one) has computed fields available. The field data will be a result of a calculation from other data. Again, the result is only available once the initial data is entered and is meant for a specific line item and not a total of all lines in the order.
So for you example you would have selection of a customer, creation of an order record, then entry of items on the order :
MainForm - Customer
Subform - Order (linked to Customer)
SubSubform - OrderItems (linked to Order)
Edit 2018-10-30:
@Tyler1 Hopefully this may help you understand what was presented above. Attached is a sample loosely based upon your provided information. This sample does not use macros. The sample contains two forms. The Customer
form contains a selection for a customer. After selecting from the listbox, select Select Customer
button. This lists all orders for that customer in a table grid. By selecting any order in that grid, the items for the order is displayed in the table grid below it. You can add new orders for a customer and new items or even modify existing orders. You can see much of how the tables are linked by viewing the internal form properties.
With form Customer1
, you can view any order with the calculated results of each line item and the order total. This is done through SQL queries.
Again as stated above, if you are absolutely requiring instant calculated results (data on Customer1 available on Customer) as you enter data, you need to use specialized macro code for your application. A sample of this type can be found in my answer here → Base Form data uneditable. Please realize macros are not something you grasp in a week or two. It takes time.
Sample ------- OrderForm.odb