How to use caluclate field with "null"?

04-05-2019 02:13 PM
New Contributor

I am trying to determine the total area that Polygon B covers in polygon A.  The only downside is if Polygon C covers polygon B then I want that area removed from the total coverage area.  I have managed to clip each B and C so that they fit in A but when I try and minus C from B it only works for the sites that have C, all of the other ones result in "null".  I've tried using an if then else statements and it refuses to calculate anything then.  Is there an easier way to cut area C out of B without the calculate field tool?

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MVP Esteemed Contributor

I suggest trying the Union tool, then you can just select the pieces you want and sum the area.