Returns a Boolean value indicating whether an expression contains no valid data (Null) or can be evaluated to 0.
IsNull(expression) |
The required expression argument is a numeric expression , string expression or object variable.
IsNull returns True if expression is Null; otherwise, IsNull returns False.
Null is not the same as Empty, which indicates that a variable has not yet been initialized. It is also not the same as a zero-length string (""), which is sometimes referred to as a null string.
This example uses the IsNull function to determine if a variable contains a Null.
Dim MyVar, MyCheck, MyStr As String MyCheck = IsNull(MyStr) ' Returns True. Trace MyCheck MyVar = "" MyCheck = IsNull(MyVar) ' Returns False. Trace MyCheck MyVar = Null MyCheck = IsNull(MyVar) ' Returns True. Trace MyCheck |
See Also |
IsDate Function , IsEmpty Function , IsNumeric Function , VarType Function |