How to use prompt values in a tuple expression

This golden nugget can save you 2 days of work - that's how long it took me to figure out the syntax.

In the tuple() you can use a member to specify which value of the measure you want. This will work much like a filter... just better.

Lest say you have a Sales measure and a Time dimension with Date at the lowest level.

You can write something like this:

tuple([Sales], [Time Dimension].[Date hierarchy].[Date]->[all].[1/1/2008])

this will get you the Sales on 1st Jan. 2008

This is great, but you want to make this a parameter, so the user can specify the date.
Maybe you have a reporting interval called ?ReportStart? and ?ReportEnd? and you want to get the Sales on the last day of the reporting interval.

You can do this:

tuple([Sales], [Time Dimension].[Date hierarchy].[Date]->[all].#sb(prompt('ReportEnd','date'))#

You can use this expression in a crosstab or graph to give you the Sales measure on the end of the reporting interval.

In more generic terms this is the syntax to use prompt parameters in tuple() expressions.