HOW TO

Auswählen von NULL-Werten aus einem Feld mit dem Werkzeug "Nach Attributen auswählen" in ArcGIS Pro

Last Published: July 21, 2023

Zusammenfassung

When selecting values from a field in an attribute table, it is helpful to use the Select By Attributes tool to choose the values including null values. By providing a query expression, the Select By Attributes tool picks the features that match the selection criteria.

In the example below, the null values in the ‘Search status’ field are interspersed with different values. The Select by Attributes tool accurately selects only the null values, which speeds up the search, in contrast to selecting the values manually.

Image of the 'Search status' field with null values

This article provides a workflow to select null values in a field using the Select By Attributes tool in ArcGIS Pro.

Vorgehensweise

The following workflow uses the is null query attribute to select multiple null values in a field.

  1. Launch ArcGIS Pro, and open the project.
  2. On the top ribbon, click the Map tab.
  3. In the Selection group, click Select By Attributes to open the Select By Attributes dialog box.
Image of the Selection group in ArcGIS Pro
  1. Configure the Select By Attributes dialog box as follows:
    1. Select the feature layer from the Input Rows drop-down list. In this example, the Trails layer is selected.
    2. Select New selection from the drop-down list of the Selection type field.
    3. Click New expression to open the query builder.
Image of the Select By Attributes dialog box
  1. In the query builder, depending on the query mode, build the following queries to select the null values:
Note: The query builder opens in Clause mode by default. To open it in SQL mode, toggle the SQL button Image of the SQL button. Refer to ArcGIS Pro: Query builder  for more information.

For Clause mode:

  1. Click the drop-down arrow, and select the desired field from the drop-down list. In this example, the Trailheads field is selected.
  2. Select the is null query from the drop-down list.
Image of Clause mode query example

For SQL mode:

<Field> IS NULL
Image of SQL mode query example
  1. Click the Verify the SQL expression is valid Image of the Verify icon icon to validate the query expression, and click OK. In this example, the expression in the SQL mode is validated.
Image of the 'Verify the SQL expression is valid' message

The image below shows the null values for the ‘Search status’ field are selected using the Select By Attributes tool in ArcGIS Pro.

Image of the null values for Trailheads field are selected using the Select By Attributes tool in ArcGIS Pro

Artikel-ID: 000024932

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