I'm working on a table to determine when an Organization first enrolled for any of our services. This could be for a Portal service which there is a Training Record for or a Data connection for which there is Interface Record. I've been able to pull back the earliest date from each table to determine when the first service was.
Here is the expression I'm using:
Case
When Min(Trn."Training Date - End Users") >= Min(InterS."Go Live Date") >= Min(InterD."Go Live Date") Then Min(Trn."Training Date - End Users")
When Min(Trn."Training Date - End Users") >=Min(InterD."Go Live Date") >=Min(InterS."Go Live Date") Then Min(Trn."Training Date - End Users")
When Min(InterS."Go Live Date")>= Min(InterD."Go Live Date") >= Min(Trn."Training Date - End Users") Then Min(InterS."Go Live Date")
When Min(InterS."Go Live Date")>= Min(Trn."Training Date - End Users")>=Min(InterD."Go Live Date") Then Min(InterS."Go Live Date")
When Min(InterD."Go Live Date")>= Min(InterS."Go Live Date")>=Min(Trn."Training Date - End Users") Then Min(InterD."Go Live Date")
When Min(InterD."Go Live Date")>= Min(Trn."Training Date - End Users")>=Min(InterS."Go Live Date") Then Min(InterD."Go Live Date")
END as "Initial Participation Date"