IIF语句MS ACCESS VBA SQL

Question

I have 3 tables

ConnectivityFile where I have the ids for some properties

CHAINDD where I have the hotel codes (they can be repeated) for the same properties

Export where I want to have all the hotel codes and their ids (a join for the previous tables)

I can achieve that with the query below

query2 = "SELECT ConnectivityFile.ID as [Hotel ID], ConnectivityFile.HotelCode  
FROM ConnectivityFile 
INNER JOIN (SELECT DISTINCT CHAINDD.HOTELCODE as [Hotel Code] from CHAINDD) as T 
ON ConnectivityFile.HotelCode = T.[Hotel Code]"

DoCmd.RunSQL "INSERT INTO Export " & query2

Now the issue I am facing is that let's say the hotel code from table CHAINDD is not present on table ConnectivityFile. I would like to point that out as "Not Connected" as the ID on the export table.

How can achieve that? I know there is the IIF statement when I have done some trial and error with no success. Where do you place the IIf statement?

Thank you very much for all your help and time

Answer 1

as long as your query actually works, the IIF goes something like this:
query2 = "SELECT IIF(ISNULL(T.HOTELCODE), ""Not Connected"", ConnectivityFile.ID) as [Hotel ID], ConnectivityFile.HotelCode
FROM ConnectivityFile LEFT JOIN (SELECT DISTINCT CHAINDD.HOTELCODE as [Hotel Code] from CHAINDD) as T ON ConnectivityFile.HotelCode = T.[Hotel Code]"

basically, if the code is there, use it, otherwise put a string staying "Not connected"
Note that the hotel code field in Export must be able to handle NON-unique data - ie: not be a primary key.