The following table describes how commands and functions interpret null values.
| Data type | Behavior |
| Logical | Most logical expressions that evaluate to .NULL. return .NULL. or generate an error. EMPTY( ), ISBLANK( ), and ISNULL( ) are exceptions. |
| Numeric | Numeric expressions that evaluate to .NULL. return .NULL. A numeric function evaluates to .NULL. when passed a null value. |
| Date | Date expressions containing null values return .NULL. |