For example, a customer may have several ... You would use Is Null and Is Not Null in query expressions and SQL WHERE clauses. IsNull(), on the other hand, is a Visual Basic for Applications ...

For example ... you’re telling SQL to take a value and compare it against every value or set of values in a list using =. If any NULL values exist, a row will not be returned–even if both ...

To do this in SQL, you specify a column as NOT NULL. NOT NULL tells SQL to only allow a row to be added to a table if there is a value for the field. For example, NOT NULL assigned to the field ...