There is a table
On the first page: names and inv. rooms. And the column in which the name matches with inv. number to bring uniqueness.
On the second sheet: lists by room number room name and number.
On the second sheet, you select the name from the drop-down list from the first sheet and stamped the number. Thus it is necessary that inventory number displayed next to the column.
Use the VLOOKUP function: the first table looking for the name selected from the drop-down list in the second table, and deduce the corresponding value of the column inv. rooms.
Works approximately with the value "True", but it gives out any numbers. If False, then figushki.
Moreover, even if I copy the value from the list on the second sheet, I search did not find it on the ground from which it was taken!