Getting All Records where Particular Column is empty in Access
This would handle both empty strings ('') and NULL values in the column.
SELECT *
FROM TABLE
WHERE Nz(PARTICULARFIELD,'') = ''
Try...
WHERE PARTICULARFIELD Is Null
Sample from Web:
SELECT [Table1].[CustomerID], [Table2].[CustomerID]
FROM [Table1] LEFT JOIN [Table2] ON [Table1].[CustomerID] = [Table2].[CustomerID]
WHERE ((([Table 2].[CustomerID]) Is Null));
See: http://www.fabalou.com/access/Queries/isnullquery.asp