SSRS Multi Value Parameter. Check whether “Select All” is selected

Question

I have a multi value parameter in my SSRS Report. I want to find out whether (Select All) is checked in that parameter.

In other words, whether all the values in th

Answer 1

For the specific use-case of showing the selected filter on your report in a textbox, here's the expression that will show "All" if "(Select All)" is selected, otherwise it will show all the selected values as a comma-separated list:

=IIF(
     Parameters!YourMultivalueParam.Count = countrows("YourDataset"),
     "All",
     Join(Parameters!YourMultivalueParam.Label,", ")
 )

(split onto multiple lines for readability)

countrows reference: https://technet.microsoft.com/en-us/library/dd255215.aspx

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Credit to other answers, just want to extend them for this common scenario.