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1. Re: Use Parameters to Select NULL Values?
David Li Oct 10, 2016 6:59 AM (in response to Alex Dixon)Hi Alex! You can try creating a Boolean parameter. Let's call it [NullsOnly], and say it's TRUE when we want to see only nulls. Then you would use this calculated field as a filter:
(NOT [NullsOnly]) OR ([NullsOnly] AND ISNULL([The Field]))
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2. Re: Use Parameters to Select NULL Values?
Alex Dixon Oct 10, 2016 7:23 AM (in response to David Li)What about when I want to set up a filter with three options? For example, NULL, Option A, and Option B? It looks like this only lets the use choose between NULL values and non-NULL values. I could be completely misunderstanding you, however.
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3. Re: Use Parameters to Select NULL Values?
David Li Oct 10, 2016 7:29 AM (in response to Alex Dixon)I wasn't completely clear about what you wanted, so I just threw out an option on that one. What would be the specific behavior of your three different options?
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4. Re: Use Parameters to Select NULL Values?
Andrew Watson Oct 10, 2016 7:30 AM (in response to Alex Dixon)Interesting one, I don't think I've come across this request before. However it feels similar to adding an All to a parameter...just in reverse. Check this post on how to add all, Business Analytics - Simple way to add all to parameter Tableau
In your case you want to return False when Null is selected - i.e. so nothing is displayed. Could also be you want to return false for the selected options as well, in which case your calculated field (filter) could be something like [Parameter] != [Field].
Interested to hear how you progress with this.
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5. Re: Use Parameters to Select NULL Values?
Alex Dixon Oct 10, 2016 7:33 AM (in response to David Li)Sorry about that! What I'm trying to do is give our advisors (I'm in the higher education industry) a breakdown of those student that they have advised (value of "Advisor"), have not advised (value of "NULL"), and an "all" option so that advisors should see their list of student (both advised and not advised).
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6. Re: Use Parameters to Select NULL Values?
Alex Dixon Oct 10, 2016 8:09 AM (in response to Alex Dixon)Ah. I just created a calculated field to change the NULL values to "None" and then set a parameter based on that. Appreciate the responses!