Thanks Marco, You've answered my question, so thank you. For reference, I've never see this in any sql rmdbs.
Some examples my help the community, hopefully I will be able to contribute sooner or later. Thanks again! Andrew On Wed, 7 Jul 2021 at 17:43, GMAIL <casalbo...@gmail.com> wrote: > This is how sql works. > You want to apply a function to one column, and the column you are > comparing must have a value. > Consider this: tag_service != 'xxx' or null != 'xxx'. Null can't be > equal or unequal to any value. Even null = null or null != null returns > false > > hth > marco > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >
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