You can search the wiki semantically using the following two tools: Special:Browse and Special:Ask
The first search form allows you to quickly list all semantic properties used in a page. You can display a list of all pages the property is used together with their respective values. However, you cannot issue a more complicated search query.
For more elaborate queries, you will need to use the second search form. This form is divided into two parts: the Query and the Additional data to display. You can search and filter the data as follows. Supposed we need to search the Virtual Reality Devices category and sort the devices by price.
Find the semantic property that you wish the data to be sorted by. In the case of our example, this will be
Virtual Reality Devices. The property's whole name has to be used, and the query must be enclosed in square brackets. Note that the query uses double
This search query displays a list of all devices that are categorised as Virtual Reality Devices but does not show any additional information. To display a price alongside the list of the devices, an additional property has to be stated in the right form field. These are additional properties found on the pages. In the case of this tutorial, we need to write
?Costs into the right form field and issue the query.
The resulting table now displays all Virtual Reality Devices together with the price (if known) of the individual devices. Additional values can be added below the
?Costs, with each being on a separate line.
All available user-created semantic properties can be found listed on the Special:Properties list.
The official Semantic MediaWiki guide offers more details.