Display fields associate???

[Tiny]

I have a number and description into the table [Item] and in my table [Invoice], I select these two fields (number and description) with the ComboBox. I would like select, by example, my number item and the field Description associate at the number displaying in her comboBox Description and vice versa. My two tables are in relations.

That must do it with the sql, but how?

Thanks for help!!