Just for fun, lets add some calculations to the groups
DECLARE @TableDate TABLE (TrxDate date PRIMARY KEY CLUSTERED, Value int NOT NULL);
INSERT INTO @TableDate ( TrxDate, Value...

You have no indexes.  So for EVERY select/update/delete, SQL has to do a full scan of the entire table in order to find the records to action.
In order to...

You really shouldn't use varchar(max) in this case.  Have you ever come across a first name, or a last name that is longer than 50 characters?
You also want to normalise...

Depending on the distribution of your data, this script by Paul White might be of use
Super-fast DISTINCT using a recursive CTE