SELECT    P_Number,
    Date,
    MAX(CASE WHEN Extension = '' THEN Reading ELSE '' END) + ';' +
    MAX(CASE WHEN Extension = 'P' THEN Reading ELSE '' END) + ';' +

I'll present two methods that I found to get the data.  Thanks for posting the DDL; it was very helpful to have something to use for testing.  If my solutions...

I don't understand what you mean by "versioning purpose".  Perhaps others don't either, which may be the reason that no one else has responded to your question.  Please explain further. ...

If you know the names of the 35 tables, you should be able to build your table first, with the 35 column names you want to use.
CREATE    --...

I don't think I cover the "full" stack, but I do much of it.  I don't do the networking or user administration for our company, or work on the website,...

Thank you for the sample data and for the desired output.  Those are much appreciated.
I still don't understand how the data relates.  In the #MainTable for Group1, I see...

You could also look at the MERGE statement, which will do inserts, updates, and deletes from a source data set to a target data set in a single statement.  There...

From your post, it seems that you want to get records of how much time users spend on various activities.  You have a log of date/time events, and need to...

I think you are trying to add the results of two different calculations.  If so, then split the calculation into two individual steps, then add the results, like this.

Jeff's earlier message said, "If you're talking about 3 and 4 part naming in any of the code itself, caveat emptor. As databases grow, they sometimes move and you end...

I found this thread, and found it helpful.  I have a different solution that may help someone else.  Here is my solution.  In short,  it brings the birthdates of each...