Select By Layers

This tool allows you to select records from layers based on their spatial relations with other layers.

Select By Layers tool window contains 8 fields:

1. In this field you can determine what you want to do. Possible options are:

1. • Select records from
   • Add to the currently selected records in
   • Remove from the currently selected records in
   • Select from the currently selected records in
2. Here you can select which layers should take part in Select By Layers operation. To select a layer please check the box on the left side.
3. This drop down list allows you to pick the comparison method for Select By Layers operation. Possible methods include:
   • intersect with
   • are within distance
   • completely contain
   • contain
   • are contained by
   • are completely within
   • have their centroids in
4. Here you can select the second layer for Select By Layers operation. This layer will be spatially compared with the layer/s selected in the field number 2.
5. In this field you can decide if the comparison should be limited to an existing selection result set.
6. This option allows you to add a buffer to records in layer selected in field number 4. Buffer will virtually increase the records area for the time of Select By Layers operation. You can enter custom distance and select the distance unit from the drop down list. Possible options are:
   • metres
   • kilometres
   • feet
   • yards
   • miles
7. Here you can set how precise (in metres) the calculations should be. Default value is 0.100 (it can be changed in the Global/Inheritable User Settings in Advanced tab.)
   
   
8. Click Select to execute the operation or Cancel to reset all settings and close the window.

Select by Layers – Guide

To explain how to use this tool we will use Tourist symbol and National Parks layers. Both these tables are part of Ordnance Survey Strategi dataset and are available for free from OS website under OS OpenData licence. You can find a description of these layers below.

• Tourist symbol – this layer stores information about tourist attractions. This is how it looks in database:

• National Parks – this layer stores details of United Kingdom National Parks.

In this example we will try to select all tourist attractions which are located in National Parks and in 10km radius around National Parks. To do so, please make sure that both layers are added to the map and click the Select By Layers tool icon.

This is how already configured Select By Layers tool looks:

Explanation:

1. We’ve chosen Select records from option because we want only to select the records.
2. Tourist symbol is a layer that we want to spatially compare with National Parks. That’s why we’ve checked it on the list.
3. In this case, National Parks are larger than tourist symbols so are contained by option will work perfectly.
4. National Parks is the second layer for our spatial compare operation.
5. We want to select windmills that are also located in 10km radius around National Parks. That’s why we’ve set 10km buffer for records in National Parks layer.

Now please click OK button to start the Select By Layers operation. This is how it worked:

On the screen you can see a national park (light green colour) and tourist attractions (blue diamond icons). Some of the tourist attractions have been marked by a red circle. These tourist attractions have been selected by Select By Layers operation. As you can see only tourist attractions which are located in National Parks and in 10km radius around National Parks have been selected and marked by the red circle. You can configure the selection styles in the Global/Inheritable User Settings in Selection Styles tab.

The Select By Layers operation have selected 584 out of 2067 records from Tourist symbol layer.

You can now use for example Copy tool to create a new layer containing only 102 selected records from Windmills layer.