Planning Analytics

I have a department dimension named "GAdepts"

In this dimension are various subsets containing specific sets of departments and they are named according to each user's legacy TM1 id.  For example, the subset for me is named "bshaver", which was my old legacy TM1 user id before we upgraded to CAM authentication several years ago.  These subsets were set up many years ago to drive which departments a user could see on webpages using SUBNM formulas.

In my "}Clients" dimension, there is an attribute named "Old TM1 Username" that stores this legacy id for each user.

I am needing an MDX query that will return the members of the department subsets based on the user that is logged in.

For example, the MDX "{ StrToMember( "[}Clients].[" + UserName + "]") }" for me returns "shaw/Bucky Shavers"

I need an MDX that will look up the "Old TM1 Username" attribute for "shaw/Bucky Shavers" which is "bshaver", and then return the contents of the GAdepts subset named "bshaver"