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Help:Semantic MediaWiki
From A Storehouse of Knowledge
Semantic MediaWiki (SMW) is a method for making information in Wikis understandable by computers. It also allows users to find more complex information than with ordinary string searches.
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Uses
The uses of SMW include the following:
- More intelligent searches. Instead of just searching for strings of text, you can search for, for example, cities with a population over five million people.
- Automatically-generated lists. Instead of creating Wiki pages of "List of largest natural disasters", and having to keep the page up to date, SMW can automatically generate (and keep up to date) such a list from the articles in the Wiki.
- Automatic measurement conversion. Instead of typing "one mile (1.6 kilometres)" into an article, you can just put in one measurement, and hovering over the text will show the measurement in other units (try it here: one mile1.609 km
80 chains).
To achieve most of these, however, special markup needs to be used.
Queries
An SMW query can find information based on categories and namespaces, and also on "properties" assigned to pages. To continue with the example above of asking for a list of all cities with a population over five million people, what you would really be asking for is a list of Wiki pages (articles) which are in the Wiki category of 'Cities' and which have a property named 'population' with a value greater than or equal to 5,000,000.
Properties first have to be created and given a type, such as 'number' or 'string'. You can also create your own types.
The Population property, for example, has a type of 'number'. The 'number' type allows for numeric sorting of populations, so that 5,000,000 is smaller than 15,000,000, whereas if they were sorted alphabetically, '15,000,000' would come before '5,000,000'.
There are some built-in types, and further types can be created.
Query formats
SMW Queries can have a format specified. Two of the main ones are list and table. See Semantic MediaWiki query format for a summary of available formats.
Types
A list of types is found here. If a type on that page has a blue link, following the link will show a list of properties using that type.
Properties
Properties are created by creating a page of the name of the property in the 'property' namespace (e.g. property:population). By default, all properties have the type 'page', unless the property page itself has the property 'has type'. So the population property page has the code [[has type::number]], which makes the 'population' property be of type 'number'.
A list of properties can be found here.
Example
The following is an example of a table produced by a SMW in-line query
- Code
This code asks for all pages with the member level property, and asks for the results to include the member level and member status properties. It also limits the table to 30 entries.
{{#ask:[[member level::]]
| ?member level
| ?member status
| limit=30
}}
- Result
The resulting table can be sorted by any column.
NB: This list relies on users having the {{member}} template on their user pages with the appropriate paramaters set.
warning.png"" cannot be used as a page name in this wiki. Some use of "<nowiki>[[</nowiki>" in your query was not closed by a matching "]]".
