keep null values with data exclusion

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04-18-2012 09:05 AM
JamesHarrington
New Contributor III
Hello

I'm classifying point symbols based on a numeric field [result]. I want to exclude and display differently any data that has a "U" in a separate field [qualifier], this can be done with the 'data exclusion' feature, but all null values will be discarded. A null [qualifier] means the [result] is valid, and shall be displayed based on the quantity classification. Is there a way to include null values without editing the field or copying the layer & reclassifying? It makes no sense to me why null values must be eliminated.

Thanks!

James
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3 Replies
MarcinGasior
Regular Contributor
I confirm this strange behavior in AG10 sp4.
Moreover, this same happens when Definition Query is set (eg. "A_strings" <> '1A' ) - besides the excluded value, all records with NULLs are excluded.

In your case, when you want to preserve NULLs, you can try:
"qualifier" IS NOT NULL
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JamesHarrington
New Contributor III
Thanks m.gasior :)

That works with a definition query, but not with quantity symbol classification using exclusions. For now, I populated all <null> values in [qualifier] with a "-" but in a table that looks like it means something. <null> indicates that the [result] is valid, so if there's anything in the [qualifier] field, that is a flag that alerts the user to a potential problem with the result.

Is there an environment setting to handle null values this way? If not, can ESRI make this available soon? There are many other instances where this has been a problem for me.
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JamesHarrington
New Contributor III
... a thought: I could change the "-" to a " " (space) so it looks blank to the user & not get tossed out as <null>...
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