Try this out. You need to compare the total number of parameters in the dataset to the count of selected parameters. The following assumes that your multivalue parameter is using a dataset called "dsRoomSizes"
="Room Size: "
& iif(Parameters!pRoomCap.Count = count(Fields!pRoomCap.Value,"dsRoomSizes"),
"Any",
Join(Parameters!pRoomCap.Value, ", "))
This expression will work in the page header/footer.
UPDATE
In the interests of finding a solution to your problem, the following should work for you. It feels hackish and I encourage you to keep research alternative methods but this will work:
- Create a second multivalue parameter and name it something like "pRoomCap_hidden".
- The source of the parameter is the exact same query
- In the parameter properties, setting the default values to the same query
- Important: Set the parameter visibility to hidden
This will create a second multivalue parameter in your report that is exactly the same as your initial multivalue parameter only this parameter list will have all values selected by default.
Enter the following expression in a textbox in your header:
=IIF(Parameters!pRoomCap.Count = Parameters!pRoomCap_hidden.Count,"All",Join(Parameters!ReportParameter1.Value,", "))
The above will compare the selected values in each parameter list. If the lists contain the same selected values then that indicates that "All" have been selected in the first list.
Like I said, it is hackish but it definitely works. Until you are upgraded to 2008, this might not be a bad workaround for you.