?? Not sure of why you would have an empty record to update, but we don't know anything about your business.
Here is your SQL formatted for readability
Code:
UPDATE tblWHO
SET tblWHO.Municipality_WHO = "na"
,tblWHO.Phone1C1 = "na"
,tblWHO.Phone2C1 = "na"
,tblWHO.FarmName = "na"
,tblWHO.FarmCivicAddress = "na"
,tblWHO.FarmCommunity = "na"
,tblWHO.FarmPostalCode = "na"
,tblWHO.Province = "na"
,tblWHO.Email = "na"
,tblWHO.Website = "na"
,tblWHO.Fax = "na"
,tblWHO.Facebook = "na"
,tblWHO.DateofEntry = "na"
,tblWHO.Notes = "na"
,tblWHO.RR = "na"
WHERE (
((tblWHO.Municipality_WHO) = "isnull")
AND ((tblWHO.Phone1C1) = "isnull")
AND ((tblWHO.Phone2C1) = "isnull")
AND ((tblWHO.FarmName) = "isnull")
AND ((tblWHO.FarmCivicAddress) = "isnull")
AND ((tblWHO.FarmCommunity) = "isnull")
AND ((tblWHO.FarmPostalCode) = "isnull")
AND ((tblWHO.Province) = "isnull")
);
"IsNull" is comparing the field value to a string --not what you intended I'm sure.
Are you trying to insert new records into a Table OR
Updating an empty record?
In SQL it is IS NULL, and doesn't use "=".
Good luck