Alteryx Designer Desktop Knowledge Base

Definitive answers from Designer Desktop experts.

Expression to Evaluate NULL Conditions

WayneWooldridge
Alteryx Alumni (Retired)
Created

When writing expressions that evaluate NULL conditions, it is a common mistake to write the syntax as:

IF [FieldX] = NULL() THEN ...

 

After all, this is how you would write the expression in SQL.  However, the actual syntax needs to be:

IF ISNULL([FieldX]) THEN ....

 

Keep writing those expressions!

Comments
Tamashiro
5 - Atom

Hello,

 

Isnull([Field_X]) == 1 for TRUE statements

or

Isnull([Fielx X]) != -1  for FALSE statements

are valid expressions?

Thanks,

Leonardo

WayneWooldridge
Alteryx Alumni (Retired)

No, that expression will not work.   You can use the expression ISNULL(Field1) and setup a Flag field as BOOL data type which will will give a True/False response or as an INT32 will give you a -1 (for True) or 0 (for False):

 

ISNULL.png