The following works:
WITH Groups AS(
  SELECT GG.groupname,
    GT.guidREP,
    GG.guidID
  FROM GuidGroup GG
   JOIN GuidTable GT ON GG.guidID = GT.guidID)
SELECT G.groupname,

Ok, what would you return if a GROUP had 3 GUID's related to it, of which 1 had a value of NULL?

Say for example Guid1 had a value...

Thanks for providing DDL and sample data. Can you explain why group 1 returns Alex twice, and group 2 John? What is your logic?

That

Table variable aren't great. Regardless of how many rows you're going to INSERT into them, the query planner will always estimate the number of rows within the table as 1....

I would firstly get your data into something of a usable format. I've used a WITH statement, but I advise actually updating your table structure. I'm also assumed that the...

Testing the following on both SQL Server 2016 Dev (Windows 10), and SQL vNext (Ubuntu 16.04.2) returns what I would expect:
Msg 208, Level 16, State 1,...

Try:
USE [WorkLSC];
GO
SELECT *
INTO [DBO.T_NEWTABLE]
FROM [WorkLSC].[dbo].[vw_OLDTABLE];
GO

Note, however, it is terrible practice naming a table with the prefix "DBO.". I would suggest...

Well... I have a solution, it's dirty, it's not pretty,it's probably got an hideous query plan, but for the 2 examples you gave, it works. If you ever have more...