WHERE (a.k.a. Slicer) Clause
The SELECT expression can also specify a WHERE clause in order to reduce the scope of a query. When a WHERE clause is not specified in a query, the entire cube space is taken into account when calculating results. When we do specify a WHERE clause the scope of the query is reduced. For example:
SELECT
[Measures].Members ON 0,
[Geography].[Geo].Members ON 1
FROM
[Sales]
WHERE
[Time].[Calendar].[Year].[2010]
In the query above, only that section of the cube where the year is 2010 is taken into account as the scope of the query. The rest of the cube is ignored. This is why the WHERE clause is called the 'slicer' - because it takes a 'slice' from the entire cube and performs calculations only on that slice of data.
To get more details about the slicer, several illustrated working examples are available from our MDX documentation pages here.
Next chapter: FROM as a Slicer.