[mapguide-users] Maestro and Nulls

[Jackie Ng]

Hi David,

I'm pretty sure the FDO filter grammar spec treats nulls as a separate
category of values which do not apply to comparison operators.

It's why we have dedicated operators in FDO to test for nullability:

   property_name NULL
   NOT property_name NULL

Instead of

   property_name = NULL
   property_name <> NULL

So to go back to your original question, I would say you amend the filter
to be this instead.

  COUNTRY NULL OR COUNTRY <> 'CANADA'

- Jackie

You wrote:

Hi Jackie,

We're encountering an issue where data is not showing up on the map when a
filter, under Layer Settings, is used and the attribute is null. For
example, if the filter is COUNTRY <> 'CANADA' any record that does not
contain a country will not show up on the map.

We're using composite styles for this specific layer and our database is
Oracle.

Thanks,
David
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