In the same table, just enter the tablename and fieldname in the criteria.
Field: FieldA
Table: YourTable
Criteria: =[YourTable].[FieldB]
That catches all matches EXCEPT when both fields are null. If you have that
case you would need to add additional criteria to test is both fields were
null on a separate line in the query criteria
John Spencer
Access MVP 2002-2005, 2007-2009
The Hilltop Institute
University of Maryland Baltimore County