Select by Attribute Back to Feature Querying and Selection Page
The Select by Attribute tool allows you to select features from layers on the map by creating an attribute query. The queries used consist of an attribute, an operator and a value e.g. you might decide to select all planning applications that were created after December 2006. To build the query you would select Planning Applications as the layer to select features from, choose Date Created as the Attribute, the operator would be 'Greater-Than' and the value would be 31/12/2006. The information is returned in the Results dialogue.
- Click on the Show Select by Attribute button on the toolbar to open the Select by Attribute dialogue.
- First choose from the drop-down field the layer that you want to select features from.
- If you untick the 'Where' box and click Run then all the features of the layers chosen will be selected.
- Keeping the 'where' box ticked to build a query, choose the attribute you want to select by from the first drop-down field on the left.
- Now choose an operator for the query. There are a number available:
Equals: selects exact match for one attribute value
Greater-Than: selects all attribute values greater in value than that specified
Less-Than: selects all attribute values smaller in value than that specified
Greater-Than-Or-Equal: selects all attribute values greater or equal in value than that specified
Less-Than-Or-Equal: selects all attribute values smaller or equal in value than that specified
Not-Equals: selects all attribute values except that specified
Like: selects all attribute values containing the partial text/number specified
(Note: input of wildcards not required; also is case-sensitive).
Contains: selects all attribute values that contain the value specified
- When choosing the value for the attribute query (in the third drop-down field to the right of the dialogue box) you can type straight in to the field or choose from all its values by clicking on the browse button beside the field. This will open an extra drop-down field from which you can choose an attribute value for your selection query.
- You can create up to four conditions for your query by choosing 'And', 'Or' or 'Exclude' from the last drop-down box in the dialogue. This will enable a extra query to be added so that you have multiple conditions.
And: requires that both conditions specified are true
Or: requires that either condition specified be true
Exclude: used to specify a condition that you do not want included in the results
- To run the selection query created for the whole of Northern Ireland, click Run. You can also confine the query to the current extent of your map canvas only, by clicking on the tick box beside 'Confine to Current Extent' prior to clicking Run.
- The Results dialogue opens automatically and contains the results of the Select by Attribute.
- To access a context menu available on the result, right click on the layer returned.
This contains a number of useful tools:
- You can choose to select all of the features returned. This is useful when there are a lot of features in the result.
- Likewise you can choose to unselect all features.
- If you have one feature selected in the results you can choose to Zoom to Selected feature, which will zoom the map canvas to the particular feature selected.
- If you have some features in the results selected, choosing Toggle Features will swap the selection to those that were previously unselected.
- To remove just that particular layer from the results window (e.g. if it is not the layer of interest to you but happens to be present at the same location as the layer that does interest you) then choose the Remove option.
- The final part of the context menu refers to Send to Select by Location. The Select by Location is a further tool for selecting features on the map and contains the buffer functionality. It is always accessed using this context menu in the Results dialogue as it processes using selections made against any layer in the map. Please refer to the Search by Location tool section for more information on this tool.
- A smaller context menu can also be accessed by right-clicking on a single selected feature in a result.
The tools in this are:
Send to Select by Location, Zoom to Feature, Pan to Feature and Remove - these tools have the same functionality as those in the context menu for the whole layer results, except that they refer only to that single selected feature rather than all the features returned for the layer.
The Pan to Feature is extra and it works by panning the map to show the selected feature instead of zooming in.
- If any or all of the Select by Attribute results are deleted from the results dialogue (but the Task title remains e.g. Task:1 Select by Attribute), the task can be refreshed so that the original results are returned again. This means you do not have to set up the query again. To carry this out, right-click on the Task title, and a context menu will appear:
Choose 'Refresh' from the context menu and the results are returned again. If you choose 'Run Task Again' the Select by Attribute dialogue will be re-opened with empty fields ready to be used again. You can also choose 'Remove' to remove the Task totally from the Results dialogue.
Example of Select by Attribute query:
Query: Select all Planning Applications in the Belfast area that were created after June 2, 2005 and have been modified by P. Murphy.
Process:
Zoom the map to the Belfast area and open the Select by Attribute tool. To run the above query, the dialogue entries would look like the following (note that the Confine to Current Extent is ticked so that only the Belfast area is queried):
Like the Identify and Select by Polygon tools, expand the results within the Results window to see all information. Any features matching the query will be returned and if these are expanded the attributes of the feature belonging to the layer that was returned can be seen.
To select any of the features so they are highlighted on the map click on the check box beside it.
Example of using Select by Attribute tool to select and highlight a building polygon on the map canvas:
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