What is a named set?
A named set is a custom "list" or "set of members". Oftentimes a named set can have just one member. And example of this would be "current day". Named sets are most commonly used on the Date dimensions.
Named Sets on the date dimension can really help "automate" dashboards and reports. It gives the analyst a "rolling/updating" member which they can use in reports and dashboards that is automatically refreshed when the cube is processed.
An example would be a named set called "current day". If this set was used in a report, the report would be filtered for the "current day". But when the cube is reprocessed tomorrow, then the "current day" would automatically be refreshed with the data. So if reports use named sets they do not have to be manually updated.
In this example, you can see that the named sets appear in Excel and they are available to be used on the rows or columns. In this case they are used on the rows.
But in the actual report, the named set is resolved to the member name. So in this case the "current day" is 04/26/2013.
The screenshot below shows some pretty common examples for some named sets. They are also very good for creating dynamic graphs. Using a named set called "last 12 months" will always give you the most current 12 rolling months. (It depends on how you define it)
Let us show you how to add named sets to you cube