SQL, iif excel cell is null then fill another excel cell - sql

Question

I have the following part of my query within excel that is not working.
iif(master.[Canada] is null or master.[USA] is null ,'USER','' ) as [Stackoverflow]
Am I doing the nulls correctly?
The logic should
1) If there is No Canada or No Usa data, put "USER" in Stackoverflow column.
2) If either Canada OR USA has data then Stackoverflow should be empty.
Currently what Im getting:
+-----------+--------------+---------------+
| Canada | USA | Stackoverflow |
+-----------+--------------+---------------+
| | | |
| | | |
| 912796NZ8 | | |
| | | |
| | US912796NZ81 | |
| | | |
| 912796NZ8 | US912796NZ81 | |
| 912796NZ8 | US912796NZ81 | |
| 912796qd4 | US912796QD43 | |
| 298785HB5 | US298785HB50 | |
+-----------+--------------+---------------+
What I am expecting:
+-----------+--------------+---------------+
| Canada | USA | Stackoverflow |
+-----------+--------------+---------------+
| | | USER |
| | | USER |
| 912796NZ8 | | |
| | | USER |
| | US912796NZ81 | |
| | | USER |
| 912796NZ8 | US912796NZ81 | |
| 912796NZ8 | US912796NZ81 | |
| 912796qd4 | US912796QD43 | |
| 298785HB5 | US298785HB50 | |
+-----------+--------------+---------------+
After changing query to iif(TRIM(master.[Camada]) = '' OR TRIM(master.[USA]) = '','USER', '') as [Stackoverflow]
It does a good job except now I still have some canada and USA data that gives me USER.
+-----------+-----+---------------+
| Canada | USA | Stackoverflow |
+-----------+-----+---------------+
| 62941ZPA6 | | USER |
| 62943Z4R0 | | USER |
| 62945ZLQ1 | | USER |
| 62950ZZE5 | | USER |
| 75585RLK9 | | USER |
| 00433JAA3 | | USER |
| 13509PEV1 | | USER |
| 13509PEZ2 | | USER |
| 62931ZLX2 | | USER |
| 62941Z8M9 | | USER |
| 62941ZYK4 | | USER |
| 62942ZV42 | | USER |
| 62943Z6T4 | | USER |
| 62946Z6Y0 | | USER |
| 62947ZWC8 | | USER |
| 62948ZTJ6 | | USER |
| 62949ZE51 | | USER |
| 75585RLK9 | | USER |
| 75585RMB8 | | USER |
| 75585RMW2 | | USER |
+-----------+-----+---------------+
Should not have USER for these 20 records.
Any help would be appreciated, thanks.

Answer 1

The Jet/ACE SQL dialect does support IS NULL. However, as your current results suggest, empty strings ('') are not the same as the NULL entity. This is especially true in Excel (a non-database application where empty cells may not default to NULL). In fact, you are actually assigning empty strings in the falsepart of your IIF() call where records without 'USER' value in [Stackoverflow] will be empty string and not NULL.
Consider extending your IIF expressions to account for zero-length strings and assigning NULL to non-matches:
IIF((master.[Canada] IS NULL AND master.[USA] IS NULL) OR
(master.[Canada] = '' AND master.[USA] IS NULL) OR
(master.[Canada] IS NULL AND master.[USA] = '') OR
(master.[Canada] = '' AND master.[USA] = ''), 'USER', NULL) As [Stackoverflow]
Even account for invisible whitespace by using TRIM():
IIF((master.[Canada] IS NULL AND master.[USA] IS NULL) OR
(TRIM(master.[Canada]) = '' AND master.[USA] IS NULL) OR
(master.[Canada] IS NULL AND TRIM(master.[USA]) = '') OR
(TRIM(master.[Canada]) = '' AND TRIM(master.[USA]) = ''), 'USER', NULL) As [Stackoverflow]

Answer 2

I think, Jet uses the IsNull() function instead of the IS NULL operator:
iif(IsNull(master.[Canada]) or IsNull(master.[USA]),'USER','' ) as [Stackoverflow]