IsNull()
Checks whether the specified expression has a null value. This function takes an expression argument of any type and returns a Boolean value. If the expression is null, the function returns the Boolean value TRUE
. If the expression has a value, it returns the Boolean value FALSE
.
Syntax
IsNull(<expression>)
Input
expression
expression
The expression to check.
Output
Boolean
Examples
Assume that you have a form in which there is a number question with the reference name number_of_cars.
- If this question is not answered, the expression
IsNull($number_of_cars)
returnsTRUE
because the answer is null, meaning that it does not contain a value of any type. - If the question is instead answered 2, the expression
IsNull($number_of_cars)
returnsFALSE
because the answer contains a value.