Stupid Me or Stupid VBA One or the other...

[ReAn]

Can someone tell me why when i break on this line, it reports rst("MechHours") is 800

If rst("MechHours") <> Null Then

But branches to the else block?

 

[KenHigg]

If not IsNull(rst("MechHours")) Then

???

 

[ReAn]

Id still like to know why you cannot use the <> (does not equal) operator.

 

[KenHigg]

I think it's just a matter of semantics' blurring your logic thinking - Does sound like it should work when you read it though

 

[MarkK]

A Null is not a value so comparing something to it is meanigless, returns a null, and will never evaluate to True.
Exercise: Debug.Print IsNull(10<>Null)

 

[ReAn]

Well, VB/VBA... unlike any other major language (aka C/C++/Java) apparantly dosent have null as a value.

IsNull() func it makes me think that it may be a flag or something.

Because in C++/Java Null has a value and object == null will return true or false.

 

[izyrider]

A's no-value value has no value.
to assign a value to the no-value value seems to be a contradiction??

izy

 

[Pat Hartman]

When you want to test for null or not null, you MUST use the IsNull() function in VBA (or IsDate() if the field is a date/time datatype) or Is Null or Is Not Null in SQL. Anything compared to null will yield Null as the result so:

Null = Null --> Null
Null <> Null --> Null
Null = something --> Null
Null <> something --> Null

So - all roads lead to Rome, er Null

Regardless of the question you ask, if one of the operands is null, the result is not true so it is false.