Filter action

[#1]

I have a table where a field can be null

I need an object (button ? - actualy a checkbox) with two possible actions: if I click on it will show only rows were the field is not null, when unclick - shows all rows. Any ideas? Thank you.

[#2]

You can use Set Analysis to handle the expressions. For not null:

Sum({<Field={*}>} Value)

For null, you may be able to use:

Sum({$-<Field={*}>} Value)

Then create a field (Choice) to hold your two choices. Then in your expression:

If(Choice='Not Null', Sum({<Field={*}>} Value), Sum({$-<Field={*}>} Value))