ISNULL()

Advantage Concepts

Advantage Expression Engine function that determines if the result of an expression is NULL.

Syntax

ISNULL(<exp>) à lNull

Parameters

<exp>  An expression of any data type.

Return Values

This function returns True if the given expression evaluates to NULL; it returns False otherwise.

Remarks

For ADT tables, this function is equivalent to EMPTY(). For CDX and NTX table types, this function will always return False because those table types do not support NULL values. For Visual FoxPro (VFP) tables, this returns True if the given expression evaluates to a NULL value; it returns False otherwise (even if the result evaluates to an empty value). NULL and empty are not equivalent when dealing with VFP tables.

Note Advantage Expression Engine functions can be used in expressions such as record filter expressions and index expressions. They are not necessarily scalars supported within SQL statements. For a list of supported SQL scalar functions, see Supported Scalar Functions.

See Also

EMPTY()