Simple Query
Select this to construct a simple map query which allows you to either show all occurences of your chosen layer or to filter that layer for occurences which fulfil specific criteria. You can choose either of the two options after selecting the 'Theme' and the desired layer within it.
Select 'Display all layer records' to display records of the selected layer.
Note: Only the first 100 records can be displayed. To get the relevant records you should define a query.
To build a query select the 'Query layer records' option and select a field of the layer to filter the datatable with an operator and a value.
In the case of numerical data, you can select from the following operators: Equals, Less Than, Greater Than, Not Equal To, Less Than Or Equal To and Greater Than Or Equal To.
The operators are Equals or Is Like for non-numerical data.
The result of the query appears in a table and you can locate individual records on the map or select 'View on Map' to display all the results of the query on a virtual layer. This layer is listed in the legend and can be turned off and on as with any other layer.
Spatial Query
You can construct an area-based query that allows you to either show all occurences of your chosen layer or to filter that layer for occurences which fulfil specific criteria.
The spatial query is similar to the simple query. You start in the same way but after giving a value for the attribute filter you have to select a spatial operator too: That Meets, That Overlaps, That Contains, Are Contained By, That Entirely Contains, That Are Entirely Contained By, That Are Spatially Equal or That Touch.
The result of the query appears in a table and you can locate individual records on the map or select 'View on Map' to display all the results of the query on a virtual layer. This layer is listed in the legend and can be turned off and on as with any other layer.
Thematic Query
Select this function to construct a thematic map. Thematic maps are based upon a data source. Colour graduation is used to display data variations across an area.
Although the procedure seems to be endless, step by step selecting the layer, the attribute, the number ranges and colour to display the different classes, you will get a virtual layer with the classified features.
Note: The virtual layers can only be removed by returning to the base map. See Map Tools.