IIf

Returns the second parameter if the first parameter evaluates True. Returns the third parameter if the first parameter evaluates False.

IIf(1, 2, 3)

Ordinal	Type		Description
1	string	Required	Any function or expression that returns a true or false result.
2	string	Required	Value to return if the expression evaluates True
3	string	Required	Value to return if the expression evaluates False

The system returns the value 123 if the @VAR variable is empty and returns the value of @VAR if it exists.