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Behavior of Null Values in Commands and Functions

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.

See Also

Concepts

NULL as a Value

NULL as a Parameter

Reference

Null Value Handling

Date Data Type (Visual FoxPro)

EMPTY( ) Function

ISBLANK( ) Function

ISNULL( ) Function

Logical Data Type

Numeric Data Type

Behavior of Null Values in Logical Expressions