[FIXED] How do I perform a GROUP BY on an aliased column in SQL Server?

Issue

I'm trying to perform a group by action on an aliased column (example below) but can't determine the proper syntax.

SELECT       LastName + ', ' + FirstName AS 'FullName'
FROM         customers
GROUP BY     'FullName'

What is the correct syntax?

Extending the question further (I had not expected the answers I had received) would the solution still apply for a CASEed aliased column?

SELECT       
    CASE
        WHEN LastName IS NULL THEN FirstName
        WHEN LastName IS NOT NULL THEN LastName + ', ' + FirstName
    END AS 'FullName'
FROM         customers
GROUP BY     
    LastName, FirstName

And the answer is yes it does still apply.

Solution

You pass the expression you want to group by rather than the alias

SELECT       LastName + ', ' + FirstName AS 'FullName'
FROM         customers
GROUP BY      LastName + ', ' + FirstName

Answered By - cmsjr

Answer Checked By - David Goodson (PHPFixing Volunteer)