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<p class="MsoNormal"><span style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US">Dear Chris and Björn,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US">yes, I have tried end_date is null first. No records are found with this although most record have NULL as end_date.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif;mso-fareast-language:EN-US">Michael<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>Von:</b> chris hermansen <clhermansen@gmail.com> <br>
<b>Gesendet:</b> Dienstag, 26. August 2025 17:45<br>
<b>An:</b> Reetz, Michael (NLPVW) <Michael.Reetz@nlpvw.niedersachsen.de><br>
<b>Cc:</b> qgis-user <qgis-user@lists.osgeo.org><br>
<b>Betreff:</b> Re: [Qgis-user] Filtering NULL values from WFS<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p style="margin-bottom:11.25pt"><span style="font-size:10.0pt;font-family:"Time new Roman",serif;color:red;background:#DBE5F1">ACHTUNG!!</span><span style="font-size:10.0pt;font-family:"Time new Roman",serif;color:black;background:#DBE5F1"> Diese E-Mail erreicht
Sie von einem Absender außerhalb der niedersächsischen Landesverwaltungs-Infrastruktur mit TLS-Verschlüsselung. Bitte klicken Sie auf keine Links oder öffnen Sie keine E-Mail-Anhänge, falls Sie den Absender nicht kennen und nicht wissen, ob der Inhalt sicher
ist.</span><span style="font-size:10.0pt;font-family:"Courier New";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">Michael and list<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">On Tue, Aug 26, 2025, 07:54 Reetz, Michael (NLPVW) via QGIS-User <<a href="mailto:qgis-user@lists.osgeo.org">qgis-user@lists.osgeo.org</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Tahoma",sans-serif">Hello group,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Tahoma",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">I’ve added a WFS-layer to a project try to define filters on different attributes. It seems not to be possible to filter
for NULL values.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">Example:</span><o:p></o:p></p>
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<span lang="EN-GB" style="font-size:10.0pt;font-family:"Tahoma",sans-serif">1932 records in total</span><span style="font-size:10.0pt"><o:p></o:p></span></li><li class="m-776803879893044476msolistparagraph" style="mso-list:l0 level1 lfo1">
<span lang="EN-GB" style="font-size:10.0pt;font-family:"Tahoma",sans-serif">376 records with a value in a date attribute</span><span style="font-size:10.0pt"><o:p></o:p></span></li><li class="m-776803879893044476msolistparagraph" style="mso-list:l0 level1 lfo1">
<span lang="EN-GB" style="font-size:10.0pt;font-family:"Tahoma",sans-serif">20 records with 2005-12-31 as value</span><span style="font-size:10.0pt"><o:p></o:p></span></li></ul>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">If I set the filter to "end_date" = '2005-12-31' the result is 20 records.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">If I set the filter to "end_date" != '2005-12-31' the result is 356 records. So only records that have an end date are
recognized. Record with NULL as end date are ignored.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">Filtering in the attribute table with “is_empty_or_null” works but only for selection.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB" style="font-family:"Tahoma",sans-serif">Is this “normal” behaviour with WFS layers or is there a way to define a filter string that work for all records?</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">Have you tried<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">end_date IS NULL<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">Generally speaking (I'm not sure about this specific case) null is neither equal nor unequal hence the need for a different logical operator, IS.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">Can you combine conditions for example<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">end_date IS NULL or end_date = '2005-12-31'<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
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