Add SQL’s Not operator to find values that aren’t Null. Using Northwind, the sample database that comes with Access, I will create a few queries to illustrate using Is Null and Is Not Null.

The difference is that the meaning of null is still conveyed without the potential need to know a column may be null and to write additional code in each query to ensure nulls are included. Similar to ...

On the surface, it may appear that the SQL clauses IN and EXISTS are interchangeable. However, they’re quite different in how they handle NULL values and may give different ...