How to access a single cell in Accsess using the Expression Builder?

Question

Microsoft Access

How to access a single cell using the Expression Builder in Access?

There is a hotel. She has clients and keeps track of them.

There are several types of rooms and their cost accordingly.
There is a calculation that a person checks in, chooses the type of room, then checks out and pays the amount of the stay. So in the database, when indicating the date of arrival and departure on the form and choosing the type of room, it should be calculated by itself how much he should pay.
But as it turned out in Access, the ComboBox does not have the Item property and the like at all, and I still did not understand how to get the sum of the number when choosing its type. I am attaching the project at the link google drive
Also there are corrections and shortcomings. This is the Control work of a student of the Faculty of Tourism. It's just why they don't understand.

If someone can help me to do it or explain how, I will be extremely grateful.

Thank you.

Answer 1

Good. What is there to think about when you just need to know. In the worst case, if you really need to see the amount: take a combobox, throw it on the form, give it a data source from your three fields Code, Description of the number and amount. Are there any questions here? Wonderful. So, then we go to the Columns property and set the number of columns - 3.
That's it. All three fields will be visible. This is a working but incorrect option.
Correct option:
- use the dlookup function
- make a request and pass the required id into it - and return the price of the room.